Figure 1. TU treatment up-regulated testosterone and Gas6/Axl expression in aging mice. (A) The serum level of testosterone. (B) The serum level of Gas6. (C) Relative mRNA expression of Gas6 and Axl. (D) Relative protein content of Gas6 and Axl. Data are mean ± SD; *P < 0.05, **P < 0.01 and ***P < 0.001 vs. WT young group; †P < 0.05 and ‡P < 0.001 vs. WT old group; &P < 0.05 and &&&P < 0.001 vs. Axl-/- young group; #P < 0.05 and ##P < 0.01 vs. Axl-/- old group; A-B: n = 8 for each group, C-D: n = 3 for each group.