FGF9 acts as a secreted FGFR ligand with mitogenic activity. Its lack of a conventional cleaved signal peptide does not imply exclusion from the ER/Golgi secretory pathway. The original human cloning abstract reports secretion from transfected COS cells, and recovered CHO-product Results document mitogenic activity and preparation-specific N termini (PMID:8321227, Results around Figure 5). The rat microsomal/secretory experiments in PMID:10506195 should not be mislabeled as direct human assays. The 2000 paper is used only at the recovered abstract scope.
Receptor recognition depends on receptor splice form and ligand construct. The 1996 receptor panel used mouse FGF9 and measured mitogenesis (PMID:8663044, Tables II–III); the 2017 human-construct work directly measured binding and ERK responses (PMID:28757146, Results/STAR Methods). Engineered truncations, monomeric mutants and receptor P252R are not natural protein products. One growth-factor core captures the biological unit rather than creating duplicate cores for binding and its downstream effects.
Dimerization, heparan-sulfate binding and receptor potency affect different aspects of signaling. Mouse N143T increased tissue distribution while reducing potency for several receptors (PMID:19219044, Figures 3–8; PMID:28757146). Human synostoses association is retained without turning inconsistent S99D/S99N narrative labels into a confident variant assertion.
Human fetal-testis expression is a developmental association, not a perturbation result (PMID:17848411, Figure 4). The adult substantia-nigra study positively identifies P31371 but does not assay substantia-nigra development (PMID:22926577, Tables 1–2). Human FGF9 rescue in a smooth-muscle cell line and rat knockdown/marker results support contextual proliferative, migratory and differentiation effects, with their reporting and organism limits retained (PMID:29118903, Figure 3E; PMID:28259995, Figures 5–6).
The complete PAINT path supports nine inherited functions with no target-path IRD; loss judgments on the FGF12 branch do not apply here. All 152 Reactome contexts retain their original source keys and have P31371 participant matches. The reviewed location is the extracellular ligand, not the catalytic activity of other complex members. Two unavailable PMID:8575785 TAS statements remain unresolved despite independent support for signaling elsewhere.
The source evidence guide provides original links, operative locators and access limits. All 179 imported source objects and the original reference findings are preserved, with no new annotations, protein products or publication quotations. The genuine configured deep-research command returned nonzero and produced no provider report; its private traces remain opaque, and no cause is inferred. These authored notes and source guide are not provider output.
The cytoplasm row retains the literal positive PAINT inference as non-core. The positive IBD at PTN000160075, inherited on the exact sequence-matched FGF9 path, supplies its support. The review now cites that method and the existing phylogeny record directly. Screening all 35 literal assertions found no intervening IRD; this verifies the recorded inheritance but is not itself a new positive localization experiment.
The trafficking studies do not prove molecular activity in cytoplasm. GO:0005737 includes cytoplasmic organelles, so ER/Golgi entry is compatible with the compartment; it does not establish where FGF9 executes a molecular function. The rat microsomal/COS experiments and the separate abstract-level secretion report remain useful trafficking evidence, with their organism and access limits intact (PMID:10506195; PMID:10713129). An endogenous human cytoplasmic mechanism remains experimentally unestablished, and extracellular FGFR engagement is still the sole core.
The PR review raised a valid distinction between presence and activity. Its selected donor examples and other FGF review decisions do not add an FGF9-specific loss experiment or a target-path IRD. They therefore do not justify converting this positive ancestral assertion into a demonstrated propagation failure. The ordinary GOA relationship qualifier remains unchanged and is not a separate grading criterion under the annotation-reviewer instructions. Source-specific uncertainty remains unchanged for the two unavailable PMID:8575785 statements. No publication quotations, new GO annotations, core duplicates or source-cache changes were introduced.