['Nonsense-mediated mRNA decay (NMD) is a RNA quality surveillance system for eukaryotes. It prevents cells from generating deleterious truncated proteins by degrading abnormal mRNAs that harbor premature termination codon (PTC). However, little is known about the molecular regulation mechanism underlying the inhibition of NMD by microRNAs.', 'The present study demonstrated that miR-433 was involved in NMD pathway via negatively regulating SMG5. We provided evidence that (1) overexpression of miR-433 significantly suppressed the expression of SMG5 (P\xa0<\xa00.05); (2) Both mRNA and protein expression levels of TBL2 and GADD45B, substrates of NMD, were increased when SMG5 was suppressed by siRNA; (3) Expression of SMG5, TBL2 and GADD45B were significantly increased by miR-433 inhibitor (P\xa0<\xa00.05). These results together illustrated that miR-433 regulated NMD by targeting SMG5 mRNA.'] Does microRNA 433 regulate nonsense-mediated mRNA decay by targeting SMG5 mRNA?