Two-way ANOVA statistical analysis.

For quantitative real time PCR data, the effect of treatment (CTR versus LES), the effect of ErbB2 over-expression (BALB/c versus BALB-neuT) and the interaction between the two factors (treatment and ErbB2 over-expression) were analyzed by two-way ANOVA test. Analysis of all ErbBs showed highly significant main effects of treatment (CTR versus LES) while the effect of ErbB2 over-expression (BALB/c versus BALB-neuT) and the interaction between the two factors (treatment and ErbB2 over-expression) was not significant. Analysis of NRG1 showed highly significant main effects of treatment (CTR versus LES) for all NRG1 isoforms analyzed; the effect of ErbB2 over-expression (BALB/c versus BALB-neuT) and the interaction between the two factors (treatment and ErbB2 over-expression) were highly significant only for NRG1 alpha, beta, type I/II. (df = degrees of freedom, E = error, P = P-value).