FIGURE 4.

Phlpp1 deficiency increases Fgf18 expression and Erk1/2 signaling. A–C, Chondrocyte micromass cultures from WT or Phlpp1^−/− mice were cultured for 3 days. A, expression levels of indicated morphogens in Phlpp1^−/− cells relative to control WT cells were assayed by real-time PCR. The control value was set to 1. *, p < 0.1; **, p < 0.05 compared with control. B, immature chondrocytes from WT or Phlpp1^−/− mice were cultured in the presence of 100 nm PD173074. Western blotting was performed with the indicated antibodies and (C) the average gray value of the normalized phospho-Erk1/2 signal was determined (n = 3, normalization against total Erk1/2). D and E, immature chondrocytes from WT or Phlpp1^−/− mice were cultured in monolayer in the presence of the indicated concentrations of the Fgfr inhibitor (PD173074), the Mek1/2 inhibitor (U0126) or vehicle control (DMSO) for 4 days. MTS assays were performed. These experiments were repeated three times. Data from a representative experiment are shown. *, p < 0.05 compared with WT vehicle-treated cells; ^#, p < 0.05 compared with Phlpp1^−/− vehicle-treated cells.