(A) Expression of MMCP-4 mRNA in IC-2 cells. The blot was hybridized with ³²P-labeled cDNA probe of MMCP-4 or of β-actin. (B) Luciferase reporter gene promoter assay in IC-2 cells that expressed +-MITF. The luciferase gene under control of the normal, deleted, or mutated MMCP-4 promoter was introduced into the IC-2 mast cell line with electroporation. Bars indicate the standard error of three assays.