CDK4 and neoplasm: That is why the presence of said tumor suppressor is relevant, several actions have been attributed to it, including as a transcription factor that expresses several genes, is an inducer of apoptosis, favors genomic stability, and regulates the cell cycle concerning it is mentioned that stop the cycle in the G2 phase, but its main effect is in the G1 phase, in which it occurs mainly by the transcriptional activation of p21, with a decrease in Cyclin D1 and CDk4 and kinases.