Progenesis was used to perform Students t-tests on the fluorescent intensity values for each spot. Those with p-values < 0.05 were considered to be significantly differentially expressed. Fold differences for each differential spot were calculated from the mean normalized volumes (average spot intensity from each gel normalized to background intensity of the gel) of controls compared to the respective metal treatment. A positive fold value represents an increase in spot intensity in the treatment compared to the control, whilst and a negative fold value represents a decrease in spot intensity in the metal treatment compared to the control.