ERBB2 and neoplasm: Flow cytometry performed using anti-HER2 affibody showed that non-permeabilized tumor cells (BerEp4+ CD45−) in all primary ascites (n = 22) and solid tumor samples (n = 10) expressed surface HER2 protein, albeit at variable levels, in agreement with the detection of ERBB2 mRNA by q-PCR (Table 2; representative data shown in Figure 3C).