CASP3 and melanoma: Accordingly, immunostaining with a fluorescently labelled antibody that binds specifically to cleaved (active) caspase 3, a hallmark of apoptosis, revealed that B16-F10 melanoma cells expressed active caspase 3 at 9 h after 30 μg/mL AN1, AN2, and climacostol treatment, whereas no specific stain was observed in vehicle-treated (control) cells (Figure 9).