A relation between INSR and cancer has been established following the observation that overexpression of functional INSRs can occur in human breast cancer and other epithelial tumours, including ovarian and colon cancer, in which the INSR may exert its oncogenic potential via abnormal stimulation of multiple cellular signaling cascades, enhancing growth factor-dependent proliferation, and/or by directly affecting cell metabolism [28–33]. Here, INSR is linked to breast cancer.