Additional evidence for GPR55-promotion of malignancy includes; (1) elevated levels of its endogenous ligand lysophosphatidylinositol (LPI) in ovarian cancers (Xiao et al., 2001) and; (2) exogenous LPI promotion of proliferation and migration of various cancer cell lines (Ford et al., 2010; Piñeiro et al., 2011). Here, GPR55 is linked to cancer.