In addition, TPAC cancer cells overexpressed Fgf9, which promotes proliferation of neuronal precursors (22), Nrg1, which has been shown to drive proliferation and/or induce myelin differentiation (23), and Nrg4, which is involved in the establishment of early sensory innervation in the skin (24) (Figure 1H). This evidence concerns the gene FGF9 and cancer.