RMCE on KH2 cells inserted a cassette that contains a modified tetracycline promoter (TREtight or Tt; expression in the absence of doxycycline is 40-fold less than with the standard tetO promoter) and a fast-maturing RFP (turboRFP; tRFP) fusion with an Mir30e-based short hairpin sequence targeting Rpa3 (shRpa3.561) into the 3'UTR.