CDK4 and liposarcoma: However, Sriraman et al. showed that in five different cell lines derived from human liposarcoma, HDM2 inhibitor nutlin-3a and CDK4/6 inhibitors palbociclib, ribociclib and abemaciclib not only fail to synergize, but even seem to antagonize each other’s therapeutic effects, despite the co-amplification of HDM2 and CDK4 genes in the used models [87].