(a–c) Immunolabelling of S2 cells transfected with pPac-gal4 and pUAS-RFP (Control, (a), or pPac-gal4, pUAS-RFP and pUAS- hopTum-l (hopTum-l GOF, (b), or pPac-gal4, pUAS-RFP, pUAS- hopTum-l and pPac-gcm (hopTum-l GOF, gcm GOF, (c) and labelled for DAPI (blue), RFP (red) and Stat92E (gray). (a,b,c) show the merge of the three channels, (a’,b’,c’) show RFP alone, (a’’,b’’,c’’) show Stat92E alone and (a’’’,b’’’,c’’’) show DAPI. Arrowheads indicate transfected S2 cells. Scale bar: 20 µm. The percentage of cells presenting nuclear Stat92E is displayed in Figure 1—figure supplement 4f. (d) Jak/Stat pathway: inhibitors of the pathway that are regulated by Gcm are in red. (e,f) Relative expression levels of Jak/Stat inhibitors in S2 cells transfected with a pPac-gcm expression plasmid (three independent assays) (e) and in embryo gcm> gcm KD (f). In both cases, the data are relative to the levels in controls as described in Figure 1f. (g) Penetrance of melanotic tumors (n > 50). (h) Relative expression levels of Jak/Stat downstream targets (apt (Starz-Gaiano et al., 2008), CG1572 (Bina et al., 2010), CG13559 (Bina et al., 2010), Galphaf (Gα73b) (Bina et al., 2010; Bausek and Zeidler, 2014) and slbo [Silver and Montell, 2001]) in hemocytes from stage 16 embryo srp(hemo)> gcm GOF. The data are relative to the levels in controls as described in Figure 1f.