ARID5B is a DNA-binding protein that binds to the 5'-AATA[CT]-3' core sequence. ARID5B probably acts as a transcription regulator. ARID5B represses the cytomegalovirus enhancer. Overexpression of ARID5B leads to induction of smooth muscle marker genes, suggesting that it may act as a regulator of smooth muscle cell differentiation and proliferation. ARID5B may be involved in lipid stores.