TP53 and neoplasm: Furthermore, orbital shaking of primary tumor cells facilitated gradual loss of p53, one of the driver genes mutated in tumor progression [63]; accumulation of WT p53 in the nucleus causes direct inhibition of Nanog expression in mouse ES cells [64] and suppression of p53 expression leads to de-repression of Nanog, which is required for maintenance of mouse ES cell self-renewal.