The PDGFR is another RTK; overexpression of wild-type PDGFR associated with neurofibromin deficiency leads to aberrant activation of downstream Ras signaling and thus contributes importantly to MPNST development, indeed, it is overexpressed in Schwann cells derived from neurofibromas and MPNST99. The gene discussed is PDGFRB; the disease is plexiform neurofibroma.