ERBB2 and breast cancer: MCL-1 protein was significantly elevated in ERBB2 amplified (ERBB2 positive) breast cancers (Fig. 2f) but intriguingly, did not significantly correlate with prognosis (Fig. 2h) and rather, exclusion of ERBB2-positive cases potentiated the association between high MCL-1 and poor prognosis P = 0.007 (Log-rank Mantel-Cox test), with 10 year survival now being stratified from 82 to 71% (Fig. 2g).