CDKN1A and neoplasm: Consistent with these data, highly increased levels of typical proteasome substrates including total and K48-linked ubiquitinated proteins and p21, accompanied by caspase-3 activation, were observed in ZnPT-treated tumor xenografts with immunohistochemistry staining analysis (Figure 7D), suggesting that proteasome is a molecular target of ZnPT in vivo.