ATF2 and neoplasm: Flow cytometry FACS analysis with annexin V and PI staining was used to determine cell apoptosis, with the early apoptotic cells in ATF2-depleted B16F10 melanoma cells being significantly lower compared to the empty vector-transfected B16F10 cells (Figure 6F), suggesting increased melanoma survival in the ATF2-depleted B16F10-induced tumor cells.