Regulation of LAPTM4B mRNA expression during follicular development using semi-quantitative RT-PCR. RNA samples were collected from bovine GC of 2–4 mm follicles (SF), dominant follicles at Day 5 of the estrous cycle (DF), ovulatory follicles 24 h after injection of hCG (OF), and CL at Day 5 of the estrous cycle (panel A), and from follicular walls (granulosa cells and theca interna) at different time-point: 0, 6, 12, 18 and 24 hours post-hCG (panel B); 0 h corresponds to day 7 dominant follicle. GAPDH was used as control gene, and showed no significant difference in mRNA expression levels among samples. Gene-specific signals were normalized with corresponding GAPDH signals for each sample. A. Expression of LAPTM4B displayed a 2-fold and 2.4-fold greater expression amounts in DF than in SF and in OF, respectively (ANOVA: P < 0.003). B. LAPTM4B expression was significantly downregulated starting at 18 hours following hCG injection compared to 0 hour (ANOVA: P < 0.029). Different letters denote samples that are significantly different (P < 0.05) when Tukey-Kramer multiple comparison test (panel A) or Dunett test (panel B) were performed. Data are presented as least-square means ± SEM, and the number of independent samples per group is indicated in parenthesis.