ERBB2 and neoplasm: As expected, the suspension of neu tumor cells derived from a MMTV-neu mouse and immediately fixed for the analysis showed a dominant diploid population (2C that corresponds to G1 diploid cells) together with a 4C peak containing both G2/M diploid cells and G1 tetraploid cells (4N) and two minor peaks 6C and 8C of hyperdiploid cells (Figure 6a).