IGF1R and colorectal cancer: For example, hyperactivation of IGF-1R has been shown to be involved in cisplatin resistance of ovarian cancer cells, while in breast and colorectal cancer cells, IGF-1R has been associated with resistance to 5-fluorouracil (5-FU).[15–17] Moreover, cross-talk between HER2 and IGF-1R by the formation of heterodimers can contribute to trastuzumab resistance.[18–20]