Treatment of the cells, particularly GSK3 siRNA or GSK3B #1 siRNA transfected cells, with celecoxib led to further reduction of FLIPL levels, which was lower than in cells treated hepatitis C virus protease inhibitors with celecoxib alone or GSK3 siRNA transfection alone. These show that silencing of GSK3 improves celecoxibs influence on downregulation of c FLIP. We further examined the effects of celecoxib along with a GSK3 inhibitor on c FLIP downregulation. Both celecoxib and SB216763 alone lowered the levels of c FLIP, but, the combination of celecoxib and SB216763 was even more powerful than either agent alone in decreasing c FLIP levels. Furthermore, the mix of celecoxib with SB216763 was also a whole lot more effective than either celecoxib or SB216763 alone in increasing DNA fragmentation and in inducing PARP cleavage. 224, 0. 320, respectively, in comparison with 0. 045 in get a grip on cells treated with DMSO. Hence, it is obvious that the mixture of celecoxib and SB216763 raises DNA fragmentation, to some greater level than the sum of that caused by celecoxib Cellular differentiation or SB216763 alone, indicating that celecoxib combined with a GSK3 inhibitor in more than additive apoptosis inducing effects in human NSCLC cells. Modulation of GSK3 Activity Alters c FLIP Levels The above mentioned information on reduction of c FLIP by GSK3 inhibition declare that GSK3 positively regulates c FLIP levels. Thus, we conducted more in depth tests to examine this finding. For this end, we first treated four human NSCLC cell lines with various pharmacological GSK3 inhibitors including SB216763, LiCl and SB415286 and then BAY 11-7821 detected c FLIP levels in cells exposed to these remedies. As shown in Fig. Reduction of c FLIP by GSK3 inhibition using a GSK3 inhibitor such as SB216763 happened early, at 3 h post exposure to SB216763 in both Calu 1 and H358 cells, suggesting that c FLIP downregulation is definitely an early event post GSK3 inhibition. Furthermore, we further restricted GSK3 by knocking down its expression using GSK3 siRNAs against B and the forms, respectively, in two NSCLC cell lines. As shown in Fig. 4C, silencing of GSK3 minimally lowered the levels of FLIPL, but not FLIPS in H157 cells, however, it lowered the levels of both FLIPL and FLIPS in A549 cells.