ERBB3 and cancer: We also noted reduced expression of other cancer-associated proteins in iSCs within the endoneurial compartment compared to those within the epineurial compartment, including ErbB3 (Stonecypher et al., 2005) and N-cadherin (Flaiz et al., 2008), both associated with dysregulated growth factor signaling in tumor growth (Aplin et al., 1998; Hanahan and Weinberg, 2000) (Figure 3).