WFDC2 and neoplasm: Because HE4 expression was significantly correlated with tumor size mentioned above, we first measured the cell viability using CCK8 reagent and found that suppressive effect on the cell growth was not an immediate cell response in MKN-28 and MGC-803 cells treated with a HE4-specific siRNA1 and siRNA2; rather, it took more than 24 h to become prominent (Fig. 4c, d).