IOSE364 cells (immortalized normal ovarian epithelial cells) and TOV-21G (clear cell ovarian carcinoma cell line) exposed to 1% PF from women with or without endometriosis (n = 6–8) at 48 h showed increased expression of FoxP3, which was induced significantly (t-test) by EPF (p = 0.016) and a trend in increased expression of Treg markers IL-10 and TGFb. Here, FOXP3 is linked to endometriosis.