CDKN1A and neoplasm: Based on the increased p53 transactivation of the p21 promoter following missense mutations at RPLARs, the importance of cellular senescence to the aging process, and the fact that p53 has a complex tumor suppression interactome, we hypothesized that the RPLARs might be involved in p53 interaction with proteins in the p53/p21 cellular senescence pathway [16].