TP53 and melanoma: In this context, STX140 activity modulated the expression of some of the hallmarks of the cellular senescence pathway, such as upregulating CDKN1A and GADDA45 genes in addition to the elevation of the expression of γH2AX (a phosphorylated form of the histone variant H2AX) and p21 proteins, p53-independently, mostly seen in resistant human melanoma cells.