When B16 melanoma cells stably expressing the fluorescent protein mCherry were implanted, apoptosis of these cells in the tumor formed in Pld2−/− mice was significantly suppressed (Fig. 2c), which was consistent with the result of immunostaining of cleaved caspase 3, a specific marker for apoptotic cells (Fig. 2d). The gene discussed is PLD2; the disease is neoplasm.