Mitotic cell cycle progression (phase-transition control)

An umbrella module that composes the three irreversible, cyclin-CDK-gated phase transitions of the mitotic cell cycle into one cycle: (1) the G1/S transition (Start / restriction point), at which growth-coupled G1 cyclin-CDK releases the G1/S transcription program and SCF-dependent destruction of the CDK inhibitor commits the cell to S phase (MODULE:g1_s_transition); (2) the G2/M transition, at which the Wee1 / Cdc25 switch activates cyclin B-CDK1 and commits the cell to mitosis (MODULE:g2_m_transition); and (3) the metaphase/anaphase transition and mitotic exit, at which SAC-gated APC/C-Cdc20 destroys securin and the mitotic cyclins, separase cleaves cohesin, and a CDK-counteracting phosphatase resets the G1 state (MODULE:metaphase_anaphase_transition_and_mitotic_exit). The unifying logic is a single oscillator of cyclin-dependent kinase activity - rising from Start through mitotic entry and collapsing at mitotic exit - whose thresholds are made irreversible by positive-feedback proteolysis (SCF at G1/S, APC/C at M/A and exit) and by mutual antagonism between CDK and its inhibitors (CKIs, Wee1, PP2A-B55). Each part here is a compact summary node that names the phase-specific cyclin-CDK holoenzyme and the proteolytic switch; the detailed decompositions live in the three referenced modules. Representative members are drawn from human, Saccharomyces cerevisiae and Schizosaccharomyces pombe. Grounded in GO:0044772 (mitotic cell cycle phase transition).

This umbrella deliberately stays at the level of the three transitions and their cyclic ordering; it does not model S-phase execution (origin licensing and firing, DNA replication), mitotic execution (spindle assembly, chromosome condensation, cytokinesis) or the checkpoint pathways that feed into each transition, each of which is or will be a separate module. The three part nodes intentionally duplicate the phase-specific CDK annotons of the referenced modules so that the umbrella page is self-contained for gene-review joins; the detailed modules are the authority on step structure. The umbrella does not use conforms_to because the conformance checker matches function-term tiers in order, which is not the relation between a summary node and a multi-part module. Deep research: no module deep-research report accompanies this file (no provider credentials were available in the authoring session; hand-writing one under a provider name is prohibited).