PTHLH and hypercalcemia disease: Beyond its well-characterized endocrine and paracrine roles in inducing hypercalcemia of malignancy [6, 7] and tumor-induced bone disease [8–11], PTHrP regulates the growth of numerous tissues through its intracrine (intracellular) effects on cell survival, proliferation, apoptosis, invasion, and migration, which can occur independent of PTHrP:PTH1R binding on the cell surface [12–15].