Muscle cell differentiation involves gene regulation at both transcriptional and post-transcriptional steps. Post-transcriptional control requires various RNA binding proteins. The multi-functional RNA binding motif 4 (RBM4) protein participates in both precursor mRNA splicing regulation and translational control in muscle cells. In myoblasts, RBM4 promotes the expression of many muscle-specific mRNAs from individual genes via its activity in modulating alternative splicing. In addition, RBM4 transiently translocates to the cytoplasm during myogenesis, where it participates in translation control. RBM4 may act in conjunction with a subset of muscle-specific microRNAs to modulate their activity in translation suppression. Overexpression of RBM4 promotes muscle cell differentiation, suggesting that RBM4 acts as a positive myogenic regulator. In this review, we discuss recent data regarding how RBM4.