GPT and liposarcoma: The giant marker and ring chromosomes comprise an amplified sequence of the 12q13-15 region, leading to the amplification of several genes.[1] In ALT/WDL and dedifferentiated liposarcoma, both MDM2 and CDK4 are regularly amplified and expressed,[75,76] resulting in overexpressed proteins which can be detected by immunohistochemical examination.[77] MDM2 binds and inhibits tumor suppressor p53, thus decreasing apoptosis.