Fig. 9. Cross-specific activation of the A. stephensi leucokinin receptor with Drosophila leucokinin (drosokinin). (A) Real-time measurements of [Ca²⁺]_i in S2 cells expressing the A. stephensi leucokinin receptor and apoaequorin in response to Drosophila leucokinin. Data are expressed as [Ca²⁺]_i (nmol l^–1) against time (s); measurements were taken at 0.1 s intervals. The trace shown is an average response (N=5). Peptide was injected at 15 s. (B) Dose–response curve. Values were expressed as maximal [Ca²⁺]–background [Ca²⁺] (nmol l^–1; mean ± S.E.M., N=5). Where error bars are not visible they are too small to reproduce.