Fig. 4.

M3 receptor-mediated activation of nuclear MAPK is increased in cells adherent to collagen type I. Serum-deprived cells were placed in suspension, and replated onto dishes coated with polylysine (pl) or collagen type I (cI). After 2.5 hours, the cells were stimulated with carbachol (100 µM) for 0 to 10 minutes. Nuclear fractions were prepared and analyzed by immunoblotting for phospho-MAPK (A) or total MAPK (B). Bands were quantitated by densitometry and values were normalized to those derived from cells adherent to polylysine at 0 minutes (carbachol treatment). Results are expressed as means ± s.e.m. from 3–4 experiments. *, Significantly different from corresponding time-matched control group. (C) The ratio of phospho-MAPK to total MAPK at each time point was calculated. The resulting values are expressed as means ± s.e.m. from 3 experiments.