May play an important role in trophoblast development and in the regulation of bone formation. Expressed in placenta, uterus and in fetal perichondrium. Expression levels were increased in both early placentas and molar pregnancies and were reduced in choriocarcinoma cells. Highly expressed in the early placenta. Expression of epil peptides in the villous cytotrophoblast is different from that displayed by the syncytiotrophoblast. In fetal tissues it was identified in the perichondrium of all four limbs, vertebrae, and ribs. It was abundant in interbone ligaments. Belongs to the insulin family.