Fig. 5

Knockdown CAT-1 or inhibition of L-arginine uptake increased cell apoptosis in a dose-dependent manner. a The cell apoptosis of RA FLSs transfected with CAT1-siRNA cultured in normal RPMI 1640 medium or L-arginine-free medium was stained with Annexin-V/PI and examined by flow cytometry. b The quantification of apoptotic cells identified as PI-negative and Annexin-V-positive staining. c The cell apoptosis of RA FLSs treated with increasing D-arginine concentrations was stained with Annexin-V/PI and examined by flow cytometry. d The quantification of apoptotic cells. The data are expressed as the mean ± SD of three independent experiments. *P < 0.05