Figure 7. ET/EGF proliferation signaling pathway in BASM.

(A) Normal BASM and (B) asthmatic BASM were grown to confluence and then growth-arrested for 24 hours in serum-free media with 0.1% BSA. Cells were pretreated with U73122 (10 μM), a PLC inhibitor; FR180204 (50 μM), an ERK inhibitor; Salirasib (6 μM), a Ras inhibitor; and LY294002 (10 μM), a PI3K inhibitor for 30 minutes. Then cells were treated with EGF (10 nM) and EGF/ET-1 (10 nM/0.1 nM). As described in the Materials and Methods section, BrdU incorporation was measured after 18 hours of stimulation. Data represent mean ± SEM from four to six separate experiments. *Significance vs. control; ⁺significance vs. ET-1/EGF; **P < 0.01; ****P < 0.001; ⁺P < 0.05; ⁺⁺⁺P < 0.001; ⁺⁺⁺⁺P < 0.001.

BASM, bronchial airway smooth muscle; BrdU, 5-bromo-2’-deoxyuridine; BSA, bovine serum albumin; ERK, extracellular signal-regulated kinases; EGF, epidermal growth factor; ET-1, endothelin-1; PLC, phospholipase C; PI3K, phosphoinositide 3-kinase.