ULBP1 and neoplasm: Moreover, TP53 can activate an anti-tumor immune response via multiple mechanisms, like the down-regulation of immune-evading signals such as PD-L1, or the up-regulation of the NK cell ligands ULBP1 and ULBP2 (Textor et al., 2011; Cortez et al., 2016; Munoz-Fontela et al., 2016).