Fig. 1.

The Ric-8B gene is expressed in proliferating cells and downregulated during differentiation. (A) mRNA levels of Ric-8B were determined by RT-PCR from total RNA samples obtained from different osteoblastic and myoblastic cell lines. ROB, primary rat diploid osteoblasts; ROS17/2.8, rat osteosarcoma cells; SaOS-2, human osteosarcoma cells; MC3T3, mouse preosteoblastic cells; C2C12, mouse promyoblastic cells. (B and C) C2C12 cells were cultured for up to 72 h in the presence of BMP-2 (300 ng/ml) to induce osteoblast differentiation (B) or in medium supplemented with 10% horse serum to induce myoblast differentiation (C). The cells were collected at the indicated times, and the Ric-8B mRNA levels were determined by RT-PCR using specific primers. Osterix, an osteoblastic differentiation marker; myogenin, a myoblastic differentiation marker.