SCF-induced downregulation of MMP-9 production of mast cell progenitors. BMCMCs and IC-2^WT cells were incubated with or without various concentrations of rSCF for 72 hours at 37°C. Dose-dependent inhibitory effect on release of proMMP-9 and MMP-9 is obvious (A and B). mRNA was purified from mast cell progenitors stimulated with or without 100 ng/mL rSCF for 6 hours. MMP-9 mRNA expression of IC-2^VECTOR cells is stable despite the addition of rSCF, but MMP-9 mRNA expression of both BMCMCs and IC-2^WT cells is markedly reduced by the treatment with rSCF (C).