ERBB2 and cancer: C35 protein expression was analysed by quantitative immunofluorescence using the HistoRx AQUA image analysis system (Camp et al, 2002) (1) to determine whether it is co-expressed with HER2 in the same cancer cells and (2) to investigate whether level of expression of protein was associated with therapeutic response to trastuzumab (Herceptin) in a retrospective clinical cohort of 122 treated patients, 32 of which were found later to be HER2 negative (Faratian et al, 2009).