CHK2 mediates germ cell loss induced by E(Pc) knockdown. a–j Control (Ctrl) [nos-Gal4/+], E(Pc) KD [nos > E(Pc) shRNA], mCherry KD [nos > mCherry shRNA], mCherry, E(Pc) KD [nos > mCherry shRNA, E(Pc) shRNA], chk2 KD [nos > chk2 shRNA], and chk2, E(Pc) KD [nos > chk2 shRNA, E(Pc) shRNA] testes stained with DAPI, germ cell marker Vasa, hub and cyst cell marker Arm, and fusome marker α-spectrin. Asterisk: hub. Scale bar: 20 μm. k Quantification of germ cell phenotype. ****P < 0.0001. Chi-square test. l Quantification of GSCs number (average ± SD). Mann–Whitney U-test. ****P < 0.0001.