FYN and breast cancer: Importantly, upregulation of FYN has been consistently observed in multiple independent studies involving drug-tolerant cancer cell lines and patient-derived xenografts treated with various drugs that have distinct target profiles, including TKIs (lapatinib, a HER2 inhibitor, against HER2 positive breast cancer Chang et al., 2022) and chemotherapy drugs (irinotecan, topoisomerase inhibitor against colorectal cancer Rehman et al., 2021; gemcitabine against pancreatic cancer Liu et al., 2022; and carboplatin against high-grade serous ovarian carcinoma (du Manoir et al., 2022; Figure 5H)).