Janus kinase (JAK)2 inhibition blocks leptin/IL-1-induced nitric oxide (NO) production and nitric oxide synthase (NOS) type II protein expression. Effect of tyrphostin AG490 and Tkip on NO production and NOS II protein expression. The effect of tyrphostin AG490 was evaluated in terms of (a) nitrite accumulation in ATDC5 cells stimulated with leptin and IL-1, and in terms of (d) NOS II protein expression. The effect of Tkip was evaluated by nitrite accumulation in (b) leptin/IL-1 ATDC5 co-stimulated cells and in (c) IL-1 stimulated cells (panel c). (e) Effect of Tkip on NOS type II protein expression in leptin/IL-1 co-stimulated cells.