SCF enhances expression of FLIP and mRNA.
(A,B) Day −5 ECFCs were washed twice with PBS and incubated in 5% serum medium for 24 hours. Day −6 ECFCs were then incubated with SCF (100 ng/mL) for up to 72 hours (A) or with SCF at increasing concentrations for 48 hours (B), and cell protein lysates were prepared at each indicated time. FLIPL (long form of FLIP) protein was determined by immunoblot analysis. (C) Without a prior incubation in 5% serum medium, day −6 ECFCs were cultured at 37°C in regular medium with or without IFNγ (400 U/mL), FasL (50 ng/mL), or SCF (100 ng/mL) for 72 hours. FLIPL protein was determined by immunoblot analysis. (D) Without a prior incubation in 5% serum medium, day −6 ECFCs were cultured in regular medium with or without SCF (100 ng/mL) for 48 and 96 hours. FLIP mRNA was determined by Northern blot analysis.