In a methylation analysis of MPNSTs, although no significant methylation changes in the NF1 gene promoter were found in the MPNST tissues (45), frequent PTEN promoter methylation was detected in NF1-associated MPNST tissues and NF1-deficient MPNST cell lines, although not in benign tumors (46). The gene discussed is PTEN; the disease is malignant peripheral nerve sheath tumor.