CAT and cancer: Our results cannot yet account for this correlation; when cells are defined in terms of their H2O2 membrane diffusion rate constant and their intracellular catalase concentration, susceptibility in terms of the inverse of the extracellular H2O2 consumption rate is not consistent with the experimental observations of cancer cells having a higher H2O2 membrane diffusion rate constant and a lower catalase concentration (see Section 2.1).