Figure 5. Barrier enhancement by FTY720 does not require PKA, PKC, PKG, or PP2A intracellular signaling.

HPAEC plated on gold microelectrodes were pretreated with the following inhibitors or vehicle for 1 h: 4-cyano-3-methylisoquinoline (4ME) (25 µM, PKA inhibitor), Dihydrochloride (H8) (60 µM, PKA and PKG inhibitor), Go6983 (Go) (1 µM), Ro-32-0432 (Ro) (1 µM), Go 6850 (Bi) (1 µM) and Calphostin C (Cal) (1 µM), (which combine to inhibit most PKC isoforms) and okadaic acid (OA) (2.5 nM, PP2A inhibitor). The range of inhibitor concentrations used is 10∼100 times of IC₅₀ provided by the manufacture. Cells were then stimulated with FTY720 (1 µM). The maximal TER increase of vehicle control plus FTY720 was set at 100, n=3 per condition. There are no statistically significant differences between any of the conditions shown.