Fig. 7. Loss of actin adhesion microspikes in reponse to rolipram or Y27632 correlates with decreased peripheral phospho-MLC and increased PKA activity. (A) REF52 cells were plated onto laminin in the presence of increasing concentrations of rolipram. Cells were fixed 1 hour after plating and stained for either Scar1 or MLC phosphorylated at Ser19. The number of cells that had formed actin adhesion microspikes under each condition – as judged by Scar1 staining – was determined and expressed as the percentage of total cells plated. Similarly, cells were scored for peripheral staining of phosphorylated MLC under each condition. In parallel experiments, cells were lysed and levels of PKA activity determined using a peptide substrate. The results shown represent the mean±s.e.m. of three independent experiments. (B) Experimental set-up like (A) except that cells were plated in the presence of increasing concentrations of Y27632.