(D) catalase activity and (E) cell viability following H2O2 exposure relative to the control (no H2O2) for wild-type, cta1 and ctt1 cells. Exponentially growing cells in YPD medium were washed twice after 12 h (OD600=0.5), suspended to the same OD600 in KPi, and challenge with 0.2-2mM H2O2 for 1.5h at 30⁰C and 225 rpm. Catalase activity and cell viability were measured as described under Materials and methods. Results are the average ±SD for three independent cultures (n=3). Lines between the data points in panels D and E were added as a visualization aid.