The function of ENSG00000106331 (PAX4, paired box 4) is as follows. DNA-binding transcription factor that plays a central role in the differentiation and development of type B pancreatic cells, which are located within the pancreatic islets of Langerhans responsible for the production and release of insulin (By similarity). Mainly acts as a transcription repressor that binds to a common element in the glucagon, insulin and somatostatin promoters and inhibits their expression (By similarity). Prevents differentiation of type A pancreatic cells, probably by repressing expression of ARX (By similarity). Competes with another transcription factor, PAX6, for this same promoter binding site (By similarity). Also plays a key role in intestinal enteroendocrine cell differentiation by (1) directly promoting differentiation of enterochromaffin cells and (2) preventing differentiation of other intestinal enteroendocrine cell types (PubMed:37883554). Prevents differentiation of other intestinal enteroendocrine cell types by repressing the expression of ARX, the master transcription factor for intestinal type-L, -N, -D, -I and -G enteroendocrine cell differentiation (PubMed:37883554). {ECO:0000250|UniProtKB:P32115, ECO:0000269|PubMed:37883554}. [Isoform 2]: Isoform 2 appears to be a dominant negative form antagonizing PAX4 transcriptional activity. .