Distinct roles for mitogen-activated protein kinase phosphatase-1 (MKP-1) and ERK-MAPK in PTH1R signaling during osteoblast proliferation and differentiation.

Parathyroid hormone (PTH) and PTH-related protein (PTHrP) activate one single receptor (PTH1R) which mediates catabolic and anabolic actions in the bone. Activation of PTH1R modulates multiple intracellular signaling responses. We previously reported that PTH and PTHrP down-regulate pERK1/2 and cyclin D1 in differentiated osteoblasts.