Flow cytometric analysis of A2L2 cells with sera from MMTV-c-neu mice vaccinated with virus-like replicon particles (VRP)-neu or VRP-hemagglutinin (HA). Immune serum from the mice (described in Fig. 4) was drawn at 133 days. The serum was analyzed at dilutions of (a) 1:25 and (b) 1:100. Filled curve, sera from VRP-neu-vaccinated mice; open curve, sera from VRP-HA-vaccinated mice. The secondary antibody, FITC-labeled goat anti-mouse IgG, was diluted in PBS (1:1000).