Reporter gene assay of ϵ constructs. (A) The ϵ-promoter with the SATB1-binding site M_ϵ was cloned 5′ of the luciferase reporter gene in pREP4/Luc. M_ϵ is mutated in mut-ϵ and deleted in Δϵ. HS-2 with the SATB1-binding site M1 was cloned 5′ of the ϵ-promoter to give HS2-ϵ. M1 is mutated in mut-HS2-ϵ and deleted in ΔHS2-ϵ. (B) The luciferase activity was determined after transfection of the reporter gene construct into K562, HeLa, and K562/SATB1 (K/SATB) cells with (▪) or without (□) cotransfection with a SATB1 expression vector as indicated. The promoterless pREP4/Luc construct was included as a negative control. Error bars represent SD from 3 independent experiments.