It has also been reported that zinc depletion induces apoptosis and decreases Sp1, Sp3 and Sp4 in cancer cell lines [32], [33], and we confirmed that aspirin-induced PARP cleavage and downregulation of Sp1, Sp3 and Sp4 was inhibited in RKO and SW480 cells cotreated with aspirin plus ZnSO4 (Figs. 7D and 7E). This evidence concerns the gene SP4 and cancer.