In prostate (PC-3, DU145 and LNCaP) and ovarian (OVCAR3 and A2780) cancer cell lines, an autocrine loop that involves GPR55, LPI and the ABC transporter ABCC1 has been demonstrated (Pineiro et al. 2011), whilst GPR55 expression enhances the invasion and migration of human breast cancer cells (Ford et al. 2010). Here, GPR55 is linked to breast cancer.