Fig 4. Effects of system y⁺ CAT1 siRNA and L-Arg’s ability on NF-κB promoter activity and NF-κB expression.

Caco-2 transfected with system y⁺ CAT1 siRNA for 24 hour prior to the transfection of pNF-κB Luc vector for 18 hours were treated with IL-1β (4ng/ml) for 4 hours after pretreatment of 4 hours of L-Arg (5 mM) (Fresh medium with L-Arg was applied after removing medium for pre-treatment). Cells were collected for luciferase activity and isolations of protein and total RNA as described in Methods. A: NF-κB luciferase activity. Data are expressed as fold-induction of normalized luciferase activity. B: NF-κB mRNA levels were determined by qRT-PCR, then normalized to β-actin. C: NF-κB p65 protein levels were measured by Western blot analysis and normalized to β-actin. Data are means ± SE. * P<0.05 (n = 6 /group).