Socs44A misexpression reduces JAK signaling in the wing. Wild-type venation (A) is compared with a viable hop mutant, hopmsv/hopM38(B). hop reduction causes ectopic vein (arrow) near the posterior crossvein. (C) Expression of UAS-Socs36E using the engrailed-GAL4 driver (e16E-GAL) produces a similar ectopic vein phenotype, plus the loss of the anterior crossvein (arrowhead). (D) Similar misexpression of Socs44A causes ectopic wing vein production near the posterior crossvein (arrow) and arching of vein L3 (arrowhead). (E) Reduction of the dosage of hop enhances the Socs44A misexpression phenotype. (F) Misexpression of hop in the posterior compartment causes dramatic vein loss, but that loss is restored by the simultaneous expression of Socs44A (G).