Neutralization of transforming growth factor β (TGF‐β), interleukin (IL)‐10, or IL‐4 did not abrogate elevated FOXP3 expression induced by SKOV3 cell culture supernatant, but neutralization of leukemia inhibitory factor (LIF) partially counteracted the effect of supernatant on naïve T cells. (A) FOXP3 expression in activated naïve T cells treated with culture supernatant (CS) of SKOV3 and neutralizing Ab against TGF‐β, IL‐10 (top), IL‐4, and LIF (bottom) on day 3 by flow cytometry. One representative staining is shown for at least three independent experiments. (B) The average percentage and range of FOXP3 expression in activated naïve T cells treated with CS of SKOV3 and neutralizing Ab against TGF‐β, IL‐10 (left), IL‐4, and LIF (right) on day 3 from at least three independent experiments.