Effects of IFNγ on SCF, EP, and IGF-I receptor mRNA expression. Day-6 ECFCs were treated with 2,500 U/mL of IFNγ for 3, 6, and 24 hours and Northern analysis was performed with specific ³²P-DNA probes for these mRNAs. (A) shows the autoradiograms of a Northern analysis indicating the level of SCF, EP, and IGF-I receptor (R) mRNA, as well as actin mRNA. (B) shows the change in the level of SCF (•), EP (▪), and IGF-I receptor (▴) mRNA and actin mRNA (▾) after densitometric scanning. Data are expressed as the percentage of actin mRNA level and means ± SD of triplicate experiments with ECFC purities of 52% ± 4%, 46% ± 2%, and 68% ± 4%.