PTH1R and osteoporosis: Unlike PTH, a β-arrestin biased PTH isoform (bPTH7-34) appears to uncouple the beneficial anabolic effects of the PTH1R activation from its catabolic and calcitropic negative side effects, thus confirming an effective role for β-arrestin in osteoporosis treatment (Gesty-Palmer and Luttrell, 2011; Luttrell et al., 2018a).