PTH1R and osteosarcoma: As a matter of fact, in oral cancer PTHrP regulates the cell motility and invasiveness via an autocrine and an intracrine pathway, respectively [28], but in osteosarcoma, loss of PTH1R induced a decrease in proliferation and an increase in tumor differentiation, not mediated by extracellular PTHrP and likely induced by an intracrine PTHrP pathway [51].