Inhibition of the LH-induced decrease in guanylyl cyclase activity in mouse follicles by the Npr2 -7E mutations. Guanylyl cyclase activity in wild-type and Npr2-7E/7E follicle membranes, measured in the presence of 1 µM CNP. Membranes were prepared from follicles with or without treatment with LH for 20 min. Each value shows the mean ± s.e.m. for 4 separate membrane preparations. The asterisk indicates that LH treatment significantly decreased the CNP-dependent guanylyl cyclase activity in wild-type follicles (P<0.05). LH treatment did not cause a significant change in CNP-dependent activity in Npr2-7E/7E follicles (n.s.).