Figure 1
From: ABCB4 is frequently epigenetically silenced in human cancers and inhibits tumor growth
Epigenetic regulation of human ABCB4.
(A). Structure of ABCB4 CpG island promoter on chromosome 7q21.12 and the ACBC4 protein. Arrow marks transcriptional (+1) start site and boxes mark exons of ABCB4. The ABCB4 protein consists of two ABC transporter transmembrane regions (ABC_membrane) and two ATP-binding cassette domains (ATB_BCD). (B). ABCB4 levels in normal tissues. Expression of ABCB4 was analyzed in RNA isolated from normal lung, breast, liver and kidney samples by real-time RTPCR and normalized to GAPDH mRNA levels. (C). Promoter assay. HEK293 cells were transfected with 1 μg of pRL-null, pRL-ABCB4 and in vitro methylated (ivm) pRL-ABCB4 promoter construct and 0.35 μg of pGL3. Cells were isolated 24 h after transfection and studied using a dual-luciferase reporter assay.
