Second, manipulation of neurofibromin expression by NF1 siRNA treatment in normal and malignant MPNST cells and NF1-GRD overexpression in malignant MPNST cells showed a perfect inverse correlation between neurofibromin and EGFR levels at both the mRNA and protein levels (Figure 2, Figure 3 and Figure 4). This evidence concerns the gene EGFR and malignant peripheral nerve sheath tumor.