<i>Simu</i> is required to prevent precocious exit of macrophages from sites of inflammation.

(a) GFP-labelled macrophages and their associated tracks at 0, 44, or 48 and 60 minutes post wounding in controls and simu mutants lacking apoptosis (simu2;Df(3L)H99). Left panels show macrophages present in field of view at 0 minutes; asterisk marks centre of wound. Central panels show tracks of macrophages that migrate to and then leave the wound (‘leavers’). Right panels show tracks of cells present at 0 minutes that remain in the field of view until 60-minutes post wounding. (b–c) Scatterplots showing percentage of macrophages that migrate away from wounds over the course of 60-minute movies of inflammatory responses in controls, apoptosis-null embryos (Df(3L)H99), simu mutants (simu2), and simu mutants lacking apoptosis (simu2;Df(3L)H99) (b) and upon macrophage-specific re-expression of wild-type simu in a simu mutant background (c); P values compared to control in (b) are P = 0.999, 0.047, and 0.031, respectively from left to right (Kruskal–Wallis test with Dunn’s multiple comparisons post-test; n = 18, 27, 25, 18); for (c) P = 0.004 (Mann–Whitney test, n = 14 and 18). (c’) Scatterplot of percentages of cells responding to wounds in simu mutants and simu mutants with re-expression of wild-type simu in macrophages (n = 14 and 18, P = 0.045, Mann–Whitney test). Genotypes are as follows: (a–b) control (w;;crq-GAL4,UAS-GFP), Df(3L)H99 (w;;Df(3L)H99,crq-GAL4,UAS-GFP), simu2 (w;simu2;crq-GAL4,UAS-GFP), and simu2;Df(3L)H99 (w;simu2;Df(3L)H99,crq-GAL4,UAS-GFP); (c) simu2 (w;simu2,srp-GAL4,UAS-red stinger/simu2;crq-GAL4,UAS-GFP/+) and simu2;UAS-simu (w;simu2,srp-GAL4,UAS-red stinger/simu2;crq-GAL4,UAS-GFP/UAS-simu). Lines and error bars show mean and standard deviation in scatterplots; scale bars represent 20 μm (a). All data used to plot graphs may be found in Supporting information file S1 Data. GFP, green fluorescent protein; UAS, upstream activating sequence.