Effect of CSC and its modulation by BSO and NAC on cell proliferation in NCI-H292. Subconfluent cultures of NCI-H292 cells were incubated for 24 h with various concentrations of CSC (A), CSC and NAC (B) or preincubated for 16 h with BSO (10 μM), followed by the addition of freshly prepared CSC (C). Next, BrdU was added and the cells were incubated for another 4 h and subsequently washed and fixed. BrdU incorporation was detected by immunocytochemistry (for details see material and methods). Horizontal bars indicate BrdU incorporation observed with TGF-α or medium alone. The results are mean ± SEM of 3 independent experiments, each performed in duplicate. Note the difference in scaling of the x-axes. * p < 0.05; ** p < 0.001; *** p < 0.001 vs medium-treated cells (Fig. 1A) or vs cells exposed to the same concentration of CSC in absence of NAC (Fig. 1B) or BSO (Fig. 1C).