Stimulation of CYR61 expression during the early onset of luteal regression. A) Representative semiquantitative RT-PCR results from CL collected 0.5 h after PGF2α (P) or saline (S; control) administration to cows on Day 6 (d6), Day 10 (d10), and Day 16 (d16) of the estrous cycle. Bovine GAPDH was the internal, loading control. B) Densitometric analysis of CYR61/GAPDH in CL collected from all animals (n = 3 at each stage; open bar, saline; black bar, PGF2α). Error bars are mean ± SD; **P < 0.01.