CASP8 and breast carcinoma: Similarly, PT/CuCl2 treatment for 24 hours induced high levels of PI-positivity in MCF-7 breast cancer cells, compared to PT or copper alone (Figure 1e) and such a treatment for 12 hours also induced PARP cleavage and decreases of full-length caspase 8 and caspase 9 (Figure 1f).