CDKN1A and cancer: The expression of cell cycle checkpoint‐, cell senescence‐ and apoptosis‐related genes, such as Cdkn1a (p21), Cdkn2a (p16) and Gadd45a, were upregulated in APM‐treated cancer cells of the four subtypes (Figure 3E), and this finding was further validated by real‐time quantitative polymerase chain reaction (RT‒qPCR) in Renca (Figure 3F), A498 and Caki‐1 cells (Figure S4D, Supporting Information).