We treated SKOV3 human ovarian tumor cells with 400 μM DFYNP for 18 h, finding that disruption of the second extracellular loop of claudin-4 significantly increased caspase-3 activation (6.7 ± 0.5 % cells caspase-3 positive) compared with cells treated with the inactive control peptide (1.9 ± 0.6 % positive cells, p = 0.0002, Fig. 2a, b). The gene discussed is CLDN4; the disease is ovarian neoplasm.