ERBB2 and neoplasm: Displacement in the MDM2 and HER2 status amid archival tumor tissues and CTC (in one case) and also the heterogeneity of MDM2, HER2, and c-MYC gene status in the CTC (amplified and non-amplified cells coexisted) suggest that CTC analyses possibly provide important insight about disease heterogeneity, clonal evolution, and clone dynamics.