p300 affects the following regulatory signalling molecules during the complex pathogenesis of the development of different tumours: c-MYC [108], c-Met, cyclin D1, Bcl2 [2], TRAIL [109], RAR and ATRA [28], Wnt/β-catenin [74], API5 [110], p53 [111], etc. p300 acts as an acetyltransferase, catalysing the acetylation of histones and nonhistone proteins, and plays an integral role in regulating tumour cell apoptosis. The gene discussed is MET; the disease is neoplasm.