Multifunctional RNA-binding protein involved in the regulation of pre-mRNA splicing, mRNA stability and mRNA translation important for cell fate decision and differentiation (PubMed:25313962, PubMed:26844700). Plays a major role in pre-mRNA alternative splicing regulation (PubMed:25313962, PubMed:26844700). Mediates preferentially muscle-specific exon inclusion in numerous mRNAs important for striated cardiac and skeletal muscle cell differentiation (PubMed:25313962, PubMed:26844700). Binds to intronic splicing enhancer (ISE) composed of stretches of GU-rich motifs localized in flanking intron of exon that will be included by alternative splicing (PubMed:25313962). Involved in embryonic stem cell (ESC) transition to cardiac cell differentiation by promoting pre-mRNA alternative splicing events of several pluripotency and/or differentiation genes. Plays a role in the regulation of mRNA stability. Binds to 3'-untranslated region (UTR) AU-rich elements in target transcripts, such as CDKN1A and MYOG, leading to maintain their stabilities. Involved in myogenic differentiation by regulating MYOG levels. Binds to multiple regions in the mRNA 3'-UTR of TP63, hence inducing its destabilization. Promotes also the destabilization of the CHRM2 mRNA via its binding to a region in the coding sequence. Plays a role in the regulation of mRNA translation. Mediates repression of p53/TP53 mRNA translation through its binding to U-rich element in the 3'-UTR, hence preventing EIF4E from binding to p53/TP53 mRNA and translation initiation. Binds to a huge amount of mRNAs (By similarity). Required for embryonic heart development, sarcomer and M-band formation in striated muscles (PubMed:25313962, PubMed:29358667). Together with RBM20, promotes the expression of short isoforms of PDLIM5/ENH in cardiomyocytes (By similarity). Interacts with EIF4E; this interaction prevents EIF4E from binding to p53/TP53 mRNA and inhibits the assembly of translation initiation complex. Expressed strongly in heart and skeletal muscles (PubMed:25313962). Weakly expressed in intestine, aorta, liver, lung, kidney, uterus and bladder (PubMed:25313962). Expressed in embryonic heart at 11.5 and 13.5 dpc (PubMed:25313962). Expressed in MyoD-expressing myoblasts at 11.5 dpc (at protein level) (PubMed:25217815). Expressed in the early cardiac mesoderm at 7 dpc (PubMed:19658189). Expressed in the cardiac crescent at 8 dpc (PubMed:19658189). Expressed in the developing heart and somites from 9.5 to 12.5 dpc (PubMed:19658189, PubMed:25313962, PubMed:25217815). Expressed in the lens, otic vesicle, heart and weakly in the mesodermal core of the first and second branchial arches at 10.5 dpc (PubMed:25217815). Expressed in all appendicular muscle masses at the forelimb and hindlimb levels and in developing head muscles at 11.5 dpc (PubMed:25217815). Expressed in appendicular muscle masses, diaphragm muscle and developing head muscles at 12.5 dpc (PubMed:25217815). Up-regulated during embryonic stem cell (ESC) differentiation into cardiomyocytes (PubMed:26990106). Down-regulated by microRNA-222 (miR-222) in skeletal muscle cells, leading in inhibition of muscle-specific pre-mRNA alternative splicing events and myoblast fusion (PubMed:26844700). The RRM domain is necessary for mRNA stability and mRNA translation regulation. Mice die in utero between embryonic days 12.5 and 14.5 (PubMed:25313962, PubMed:29358667). Show multiple cardiac malformations, including defective endocardial cushion morphogenesis, ventricular septum defects, reduced trabeculation and compaction and dilated atria (PubMed:25313962, PubMed:29358667). Display loss of sarcomeres in cardiomyocytes (PubMed:25313962). Show aberrant pre-mRNA alternative splicing of key genes necessary for sarcomere formation and cardiogenesis (PubMed:25313962).