Down-regulates MYOD1 expression and may up-regulate MYF5 expression (PubMed:19829708). May regulate microRNA (miRNA) transcription, up-regulating the expression of some myogenic miRNAs, including MIR1-1, MIR133A2, MIR133B and MIR206 (PubMed:24145033). Impairs the differentiation of myoblasts and may be involved in muscle regeneration (PubMed:18723017, PubMed:36882853). Reduces DUX4-induced nuclear localization of CTNNB1/beta-catenin and its subsequent activation of target genes (PubMed:36158201). {ECO:0000269|PubMed:18723017, ECO:0000269|PubMed:19829708, ECO:0000269|PubMed:24145033, ECO:0000269|PubMed:36158201, ECO:0000269|PubMed:36882853}. This is the function of DUX4L9 (double homeobox 4 like 9 (pseudogene), Ensembl gene identifier ENSG00000224807).