When the same cancer cell lines (MCF-7, LN-229, U-373) were exposed to purified Laz protein (≥ 1 μg ml−1), cancer cells showed a marked increase in caspase 3/7 activity (Fig. 6), indicating induction of apoptosis, albeit lower than that induced by VNP-Laz. This evidence concerns the gene CASP3 and cancer.