FIGURE 3. VPA effects on Dictyostelium aggregation are due to modulation of InsP₃ signalling.

a, Basal InsP₃ levels were measured with and without treatment with VPA. b, Expression of the inositol-1-phosphate synthase gene was assessed by northern analysis. Cells were treated with 10 mM lithium, 1 mM VPA, in the absence or presence of 10 mM inositol. Increased ino1 expression is shown relative to Ig7 (loading control). Ethidium stained rRNA is also shown. c, Aggregation of wild-type Dictyostelium cells and a mutant lacking the gene that codes for prolyl oligopeptidase (dpoA) in 0, 0.5 and 1 mM VPA.