Regulation of GAG secretion in the conditioned media of cultured young and aged porcine VICs by exogenous TGFβ1, its inhibitors, biomechanical strain and aging. “None”, no treatment; “T+S”, TGFβ1 + SB431542; “T+U”, TGFβ1 + U0126; “S+U”, SB431542 + U0126; “All”, TGFβ1 + SB431542 + U0126. #, vs. none, p<0.001; †, vs. T, p<0.05.