However, despite lack of ligand-binding EGFRvIII has a constitutively active receptor tyrosine kinase and is able to transform fibroblasts and to confer enhanced tumorigenicity to cancer cells both in vitro and in vivo (Huang et al, 1997; Damstrup et al, 2002; Pedersen et al, 2004). This evidence concerns the gene NTRK1 and cancer.