Fig. 4. (A) BrdU uptake in E12.5 neurosphere cells in response to fibroblast growth factor (FGF2) (20 ng/ml). (B) BrdU uptake in P0 neurosphere cells to increasing concentration of FGF2. Note the reduction in cells stained for BrdU in the tenascin C (TNC) null neurospheres at both ages. Results represent mean±s.e.m. of three independent experiments. ^*P<0.05, ^***P<0.001, using Student's t-test. (C) Expression of epidermal growth factor receptor (EGFR) in neurospheres grown in FGF2 assessed by Western blotting. One of three independent experiments is presented, with all three giving the result shown. Cells lacking TNC show enhanced sensitivity to the inhibitory effects of bone morphogenic protein 4 (BMP4), as discussed in the main text.