CASP3 and infection: By contrast, under our conditions, direct infection with a non-pathogenic yeast, S. cerevisiae, resulted in little to no keratinocyte death, thus confirming that the observed keratinocyte death was due only to the pathogenicity of C. albicans. In addition, a 1.5-fold increase in caspase 3 activity was detected, indicating the induction of apoptotic keratinocyte death (Figure 2B and Figure S1).