In human embryonic kidney HEK293 and human colon cancer HCT116 cells, p53 regulated purine metabolism through a p53-miR-34a-IMPDH pathway (miR-34a is a master regulator of tumour suppression) and consequently, miR-34a-mediated inhibition of IMPDH perturbed the GTP-dependent Ras signalling pathway [137]. The gene discussed is TP53; the disease is malignant colon neoplasm.