IGF1R and colonic neoplasm: Because IGF-IR is overexpressed in the proliferating cells at the base of the colonic crypts, which could be considered the colon tumor-initiating cells (115), and Wnt/β-catenin signaling plays a critical role in stimulating colonocyte proliferation (116), it is possible that the interplay between these two pathways could contribute to the expansion of colon tumor-initiating cells pool.