PRL and cancer: The antiangiogenic protein hormone vasoinhibin, which is generated by the proteolytic cleavage of prolactin (PRL), is of interest in the context of various diseases, including vasoproliferative retinopathies and diabetic macular oedema (1, 2), peripartum cardiomyopathy (3–5), preeclampsia (6–8), inflammatory arthritis (9, 10), and cancer (11, 12).