EGFR and malignant peripheral nerve sheath tumor: This variation in expression pattern might have been due to several factors; the most important one might be the gene dosage of EGFR. In the study by Holtkamp et al., FISH analysis revealed increased EGFR dosage in 28% of MPNST, and level of EGFR protein expression was significantly associated with increased EGFR gene dosage [19].