Smurf2 knockdown downregulates cell proliferation. Smurf2 knockdown decreases proliferation of MDA-MB-231 and MCF-7 cells which was measured with an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay (A, B) and BrdU (5-bromo-2′-deoxyuridine) cell proliferation assay (C, D). Result represented as mean ± standard deviation (n = 3). The inhibition effect on cell proliferation is more significant at 48 hours rather than 72 hours posttransfection, after which proliferation gradually increased, probably due to transient transfection. Expression of PCNA (Proliferating cell nuclear antigen) was found to be downregulated in Smurf2 knockdown cells of (E) MDA-MB-231 and (F) MCF-7, 48 hours posttransfection.