Fig. 5. MAPK activity is required for IP₃R1 MPM2 phosphorylation of mouse eggs. (A) IP₃R1 MPM2 (upper panel) and IP₃R1 (lower panel) reactivity in oocytes matured in vitro (IVM) in the presence of U0126 (25 µM), in its absence or in the presence of U0124. Quantification of IP₃R1 MPM2 reactivity is shown in the graph. (B) MPF and MAPK activities were assayed in the presence or absence of U0126 at the same time points as in A and are quantified in the graph below; asterisks indicate statistical significance. (C) IP₃R1 MPM2 (upper panel) and IP₃R1 (lower panel) reactivity in PN-stage zygotes treated with OA (10 µM), OA+U0126 (75 µM) or OA+roscovitine (Ros; 75 µM). The graph shows quantification of MPM2 reactivity. (D) Effect of OA on MPF and MAPK activities in PN-stage zygotes and inhibition of its effects by U0126 but not by Ros (not shown). The graph shows quantification of the effect of OA and U0126 on MPF and MAPK activities. Bars with asterisks are significantly different from those without a symbol.