EGFR and cyst: Interestingly, while the expression of caEGFR or the co-expression of sSpi and EGFR in cyst cells caused a phenotype shortly after the shift to 29°C, expression of sSpi (cyst cell-sSpi-testes) or the EGFR (cyst cell-EGFR-testes) alone using either of the two cyst cell Gal4-transactivators did not have an effect on the cysts (n>30, Table 2).