Cell cycle progression at G1 phase

Cell cycle progression at G1 phase is a critical cellular process determining whether a cell will commit to DNA replication and subsequent division. It is tightly regulated by sequential activation of cyclin-dependent kinases (CDKs) complexed with G1 cyclins (cyclin D and E), inactivation of the retinoblastoma (RB) protein, and transcriptional activation by E2F family members. Checkpoints within G1 ensure cells have sufficient nutrients, growth signals, and undamaged DNA before entry into S phase. Key regulatory molecules such as CDK4/6, CDK2, cyclin D/E, mTOR, and tumor suppressors like RB and p53 govern passage through G1. Dysregulation of this process, often through mutation or aberrant signaling in these regulators, is a hallmark of cancer and is a frequent therapeutic focus in oncology[1][2][3][4][5][6]. However, "cell cycle progression at G1 phase" itself is not a singular protein or receptor, but a collective designation for all these governing mechanisms and their orchestrated activity.

Other names

G1 phase progressionG1/S transition (process)G1 restriction point controlG1 checkpoint regulation

Inhibition of cyclin-dependent kinases (arrests cells in G1 by blocking phosphorylation of RB protein); Inhibition of mTOR signaling (prevents passage through cell growth checkpoint in G1); Activation or restoration of p53 (triggers cell cycle arrest or apoptosis via G1 checkpoint); Inhibition of PI3K/AKT signaling (impairs growth factor signaling required for G1 progression)