One explanation for the pleiotropism of miR-31 in different cancers was presented in an elegant study by Creighton et al. [11], wherein the authors demonstrated that the tumor-suppressive function of miR-31 in ovarian cancer was dependent on loss of p53, i.e., miR-31 only inhibited ovarian tumor cells expressing non-functional p53 [11]. This evidence concerns the gene TP53 and cancer.