A study provided in vitro evidence for the successful pharmacologic inhibition of CDK4/CDK6 activity in myoblasts and RMS-derived cells34; in this study, most ARMS-and ERMS-derived cell lines and tumor samples expressed CDK4 and CDK6, and exposure of these cells to a CDK4 inhibitor caused G1 cell cycle arrest, which is closely associated with myogenic differentiation. Here, CDK4 is linked to neoplasm.