CDKN1A and cancer: Cellular senescence, defined as a cellular condition, in which the expression of the cyclin-dependent kinase inhibitors, such as cyclin dependent kinase inhibitor 1A (CDKN1A, also known as p21CIP1) and/or cyclin dependent kinase inhibitor 2A (CDKN2A, also known as p16INK4A) causes an irreversible cell-cycle arrest, is evident in aging, which has been largely seen in cancer and aging investigations[1,115].