Loss of NF1 heterozygosity, resulting in absent neurofibromin expression, is required for benign and malignant tumor formation (Bajenaru et al., 2001; Basu et al., 1992; Bollag et al., 1996; DeClue et al., 1992; Feldkamp et al., 1996; Guha et al., 1996; Gutmann et al., 1994, 2000; Lau et al., 2000; Legius et al., 1993; Powers et al., 2002; Side et al., 1997; Staser et al., 2013; Xu et al., 1992). This evidence concerns the gene NF1 and neoplasm.