These include physiological functions such as brain development (LPAR1), embryo implantation (LPAR3), blood vessel formation (LPAR4 and LPAR6), and hair follicle development (LPAR6), and has also been implicated in pathological conditions such as the development of fibrosis (LPAR1), endometriosis (LPAR3) and obesity (LPAR4). Here, LPAR4 is linked to obesity due to melanocortin 4 receptor deficiency.