Epithelial cells that reached confluence in the four-well plates
were used for this experiment. The cells were incubated with
serum-free DF (DMEM/Ham’s F-12 1:1 (vol/vol) supplemented
with 0.1% BSA, 5 mg/ml holo-Transferrin (Sigma–Aldrich), and
2 mg/ml insulin (Sigma–Aldrich)) at 38.5, 39.5, 40.0, and
40.5 8C for 24 h. After incubation, the medium was collected in
a 1.5 ml tube containing a 1% stabilizer solution (0.3 mol/l
EDTA and 1% (w/v) acetylsalicylic acid, pH 7.3), and the
concentrations of PGE2 and PGF2a in the medium were
measured by enzyme immunoassay