TS siRNA downregulation in A549 clonal populations.

A549 clonal cell populations (NC-3, NC-10, and NC-30, each with stably-incorporated control, non-targeting scrambled shRNA; and 2–6 and 2–18, each with stably-incorporated anti-IDO shRNA) were seeded and grown overnight. Thymidylate synthase (TS) siRNA numbers 3 or 4, or scrambled, non-targeting control siRNA, were transiently transfected into each clonal population. Cells were lysed and protein was harvested 96 h later. TS and actin protein levels were determined by immunoblot. Results were quantified for each clone separately. A: TS protein quantification for each clonal population. Each bar represents the mean of 3 values (n = 3) ± SEM. *Significant difference from the same cells transfected with scrambled control, non-targeting siRNA, Student's t-test, pB: Representative immunoblots of TS and actin protein in clone NC-3 after transfection of TS siRNA (siRNA numbers 3 and 4) or scrambled, non-targeting control siRNA (C2). C: Representative immunoblots of TS and actin protein in clone 2–18 after transfection of TS siRNA.