CDK4 and cancer: Dysregulation of the mTORC1 signaling pathway is associated with pathological conditions, including cancer, obesity, diabetes, and neurodegeneration [26]. In certain types of cancer, overexpression of mTORC1 occurs due to Tuberous sclerosis protein 1/2 (TSC) phosphorylation and inactivation by Cyclin D1–CDK4/6.