TP53 and cancer: ASPP1 and ASPP2 promote apoptosis, whereas iASPP inhibits it.1, 2 Because evasion of apoptosis is a hallmark of cancer, it comes as no surprise that apoptosis enhancer ASPP1 has been frequently observed to decrease at mRNA and/or protein levels in human cancers.3, 4, 5 So far, the anticancer activity of ASPP1 is largely dependent on p53, the precise nuclear localization is thus critical.