SCF activation of c-kit response pathways in SKT6-EE372 cells. (A) SCF/c-kit induced transcription of c-myc and c-myb genes in SKT6-EE372 cells. SKT6-EE372 cells were cultured for 10 hours in 0.2% FBS and were exposed to Epo (20 U/mL), EGF (25 ng/mL), or SCF (100 ng/mL) for 0, 90, or 180 minutes. At the indicated intervals, cells were lysed, total RNA was isolated, and levels of c-myc, c-myb, and cis transcript expression were analyzed by Northern blotting. Equivalence in loading was assessed by hybridization to a 7S rRNA cDNA probe. (B) c-kit transcript expression levels are not downmodulated during Epo-induced SKT6 cell hemoglobinization. SKT6 cells were exposed to Epo at 10 U/mL and, at the indicated intervals (0, 48, and 72 hours), levels of c-kit, Epo receptor, and β^maj-globin transcripts were assayed by Northern blotting. Equivalence in loading was assessed by hybridization to a ³²P-GAPDH cDNA.