Most notably, the genes coding for WAP four disulfide core domain protein 14 (WFDC14, also named elafin), WAP four disulfide core domain protein 4 (WFDC4 also named SLPI), WAP four disulphide core domain protein 1 (WFDC1, also named PS20) and WAP four disulphide core domain protein 2 (WFDC2, also named HE4), have been studied on ovarian cancer. The gene discussed is PI3; the disease is ovarian carcinoma.