Although the detailed mode of action has not yet been elucidated, we discovered the noble implication of VPA as an HDAC1 inhibitor to facilitate CCN1-induced osteogenic differentiation of MSCs in addition to its original pharmacological roles as a drug for treating epilepsy and bipolar disorder [14], as well as a potential anticancer reagent [47]. The gene discussed is HDAC1; the disease is epilepsy.