CDK4 and dedifferentiated liposarcoma: The amplification of the 12q13-15 region, which includes key biomarker genes such as MDM2, FRS2, CDK4, as well as B4GALNT1, is a hallmark of DDLS (Dei Tos, 2000; Conyers et al., 2011; Jing et al., 2021; Nishio et al., 2021).