TP53 and cancer: However, for miR34A these obstacles may be overcome: Studies of many different cancer cell types including the present study suggest that miR34s for the larger part are downregulated by promoter hypermethylation, and we show that miR34A-5p can be upregulated by a demethylating agent in DLBCL cells with a methylated MIR34A promoter in cells with and without TP53 mutations.