FIG. 6.

mim-1 enhancer and mim-1 promoter cooperate in the activation of the mim-1 gene by Myb. Reporter genes containing only the mim-1 promoter or the mim-1 promoter and mim-1 enhancer are shown schematically at the top. The arrows indicate the orientation of the insert fragments relative to the mim-1 promoter. (A) The luciferase reporter plasmids indicated at the bottom were electroporated together with the β-galactosidase plasmid pCMVβ into BM2 cells or transfected into DF-1 cells. The cells were harvested 24 h later and analyzed for luciferase and β-galactosidase activities. Bars show the average luciferase activity normalized with respect to the β-galactosidase activity. The activity of the plasmid containing only the mim-1 promoter (pGL3-240-Luc) was designated 1. The T bars show standard deviations. (B) 10.4 cells were transfected with the indicated luciferase reporter genes (5 μg) and 0.2 μg of the β-galactosidase plasmid pCMVβ. The cells were then grown for 24 h without (white bars) or with (black bars) 2 μM β-estradiol, and the luciferase and β-galactosidase activities were analyzed as described for panel A except that the activity of each reporter gene in the absence of β-estradiol was designated 1. (C) HD11 cells were transfected as described for panel B except that v-Myb expression vector (pCDE26v-myb; 5 μg) was included (black bars). Controls contained an equivalent amount of empty expression vector (white bars). Luciferase and β-galactosidase activities were analyzed as for panel A. The activity of each reporter gene in the absence of v-Myb was designated 1.