TNF-α was associated with activity of Rab5 through the JNK pathway. (A) Ca9-22 cells were transfected with an expression vector with inserted GFP-Rab5 gene. The transfected cells were preincubated with MAP kinase inhibitors, including a p38 inhibitor (SB203580, 5 μM) (indicated as “SB”), JNK inhibitor (SP600125, 1 μM) (indicated as “SP”) and ERK inhibitor (PD98059, 5 μM) (indicated as “PD”), at 37°C for 1 h and were then incubated with TNF-α for 3 h. The active form of Rab5 in the cell lysates was subjected to a GST-R5BD pull-down assay and was analyzed by Western blotting with anti-GFP antibodies as described in Methods. (B) Level of the active form of Rab5-GTP was normalized to total GFP-Rab5 and quantified by a densitometer. (Means ± deviations [SD] [n = 3]). *, P < 0.05 versus control.