CDK4 and leiomyosarcoma: However, a large group of STS, e.g. MFH/UPS, leiomyosarcoma, and dedifferentiated/pleomorphic liposarcoma, lack known specific recurrent alterations and are characterized by a multitude of rearrangements, amplifications, deletions, and somatic alterations, including mutations in TP53, deletions of RB1 and CDKN2A, and amplifications of MDM2 and CDK4 [2,3].