IGF1R and adenocarcinoma: Furthermore, while most of the increased expression of RTKs was in adenocarcinoma, two RTKs were expressed at relatively higher levels in SCC: the neurotrophic tyrosine kinase receptor, type 2, TrkB (p<0.001), which is involved in neuronal differentiation and cell survival (Table 1, Figure 1B) and insulin-like growth factor receptor (IGFR, p<0.001).