However, we did observe that 45% (n = 22) of testes with fruΔB cyst cell clones had TUNEL-positive, fru-mutant cyst cells, which was not observed in testes carrying control cyst cell clones (0%, n = 8), suggesting that fru may function in later cyst cell survival in addition to CySC maintenance. Here, ZBTB22 is linked to cyst.