Breast cancer cells expressing FGFR1, transduced with FGFR1 or amplified with FGFR1 were resistant to CDK4/6i (O'Leary et al., 2018; Wander et al., 2020; Formisano et al., 2019; Mao et al., 2020; Finn et al., 2020). The gene discussed is CDK4; the disease is breast cancer.