LGALS4 and cyst: We also confirmed that RNAi knockdowns of caf1-55KD, rpn7 and Fs(2)Ket in cyst cells led to tumor-like germ cell cluster formation (Figure S8), but with relatively low penetrance compared to not1KD. Note that we performed pilot experiments using the c587-Gal4 driver to reveal spermatogenesis defects in case of knockdowns of the selected genes.