One of the potential mechanisms that underline the DNMT3B-mediated arrest involves the ability of DNMT3B siRNA to reduce the expression of different cyclins (Cyclin B1, Cyclin D1 and Cyclin E2) and to block the pRB/E2F1 pathway by inducing de-phosphorylation of RB tumour suppressor. The gene discussed is RB1; the disease is neoplasm.