FIGURE 1. Specific up-regulation of GADD45β mRNA by BMP-2 in chondrocytes.
Monolayer cultures of the human chondrocyte cell line C-28/I2 were treated as indicated, and total RNA extracts were analyzed by real time PCR. Each value was normalized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in the same sample and shown as the mean ± S.D. of triplicate cultures. A, GADD45β mRNA levels were increased in cultures of the human chondrocyte cell line, C-28/I2, after treatment with BMP-2 for 1 h but not with EGF, bFGF, or IGF-I. B and C, incubation of C-28/I2 cells with BMP-2 for 1 h did not increase the levels of GADD45α or GADD45γ mRNA. D, time course of BMP-2-induced GADD45β mRNA in C-28/I2 cells showed transient induction with a peak at 1 h. E, treatment of primary human articular chondrocytes with BMP-2 for 1 h increased the levels of GADD45β mRNA by 2-fold.