Inhibitors of P4/PGR action and EGF signaling decreased the levels of mRNA for PTG synthases and transporters and EGF-like factors. Primary hGLCs were treated with or without (A) RU486 (20 µM) or (B) AG1478 (10 µM) in the absence or presence of hCG (1 IU/mL) for 6, 12, or 24 hours. (A and B) The levels of mRNA for PTG synthases (PTGS2, PTGES, and AKR1C1), transporters (SLCO2A1 and ABCC4), EGF-like factors (AREG and EREG), and PGR were measured by quantitative PCR. The levels of transcripts were normalized to those of RNA18S5 mRNA in each sample (n = 4 to 6 independent experiments). Bars with no common superscripts in each time point are significantly different (P < 0.05). (C) Western blot analyses were performed with whole cell lysate (30 µg) to detect PTGS2 and PTGES protein. β-actin (ACTB) was used as a loading control. Experiments were repeated three times with independent samples.