TP53 and cancer: However, this interpretation is debatable, as it has been shown that p21 does not necessarily protect cancer cells from apoptosis induced by Nutlin-3.14 In any case, our results show that even if Nutlin-3 and TSA may weaken each others' effects in the short-term, long-term cotreatment of HCT116 p53+/+ cells with Nutlin-3 and TSA is still more toxic than either treatment on its own (Figure 8c).