(a) GSK3β upregulated the protein level of c-FLIP in H1299 cells treated with TRAIL. H1299 cells treated with LiCl (20 mM, 8 hours) and/or TRAIL (20 ng/ml, 8 hours) were harvested for Western blot analysis with the indicated antibodies. (b) Effect of hnRNPK overexpression on c-FLIP protein stability by Cycloheximide (CHX) chase experiments. H1299 cells transfected with either 2 μg Flag-hnRNPK or Flag-vector plasmids were treated with 10 μg/ml CHX for the indicated durations, then subjected to Western blot analysis with the indicated antibodies. (c) Effect of hnRNPK overexpression on c-FLIP protein stability by dose-response experiment. H1299 cells were transfected with Flag-hnRNPK or Flag-vector plasmids at the indicated doses and stimulated with CHX (10 μg/ml, 2 h), then subjected to Western blot analysis with the indicated antibodies. (d) Effect of hnRNPK on c-FLIP protein stability was dependent on the Ser9 phosphorylation state of GSK3β. H1299 cells transfected with Flag-hnRNPK or Flag-vector plasmids were stimulated with CHX (10 μg/ml, 2 h), TRAIL (20 ng/ml, 8 hours), or LiCl (20 mM, 8 hours) as indicated, then subjected to Western blot analysis with the indicated antibodies.