The p38 specific inhibitor, PD169316, prevents increases in the COX-2 expression in cTAL cells exposed to low-salt medium. Quiescent cTAL cells were maintained in DME/F12 medium (lane 1), incubated for 6 hours in low-salt medium alone (lane 2), or in low-salt medium in the presence of MEK1 inhibitor, PD98059 (1 μM) (lane 3); p38 MAP kinase inhibitor, PD169316 (1 μM) (lane 4); PKA kinase inhibitor, H8 (1 μM) (lane 5); PKC kinase inhibitor, H7 (1 μM) (lane 6); or adenylate cyclase inhibitor, dideoxyadenosine (100 μM) (lane 7) (n = 5). AP < 0.01 compared with control. Inset: representative experiment.