The two LXXLL motifs in the N-terminal activation domain of HBZ are required for activation of Dkk1 expression. (A) A schematic representation of domains in HBZ and locations of mutations that were tested. AD denotes activation domain. BR1, 2 and 3 denote basic region 1, 2 and 3, respectively. ZIP denotes leucine zipper. (B) Levels of Dkk1 mRNA in cells transfected with the indicated expression vectors. Levels of Dkk1 mRNA were normalized to UBE2D2 mRNA following quantitative real-time PCR of reverse transcribed total cellular RNA. The graph shows data from three or more independent transfections, with Dkk1 mRNA levels shown relative to values obtained from cells transfected with the pcDNA3.1 empty vector (set to 1). Lower panels show a Western blot analysis of cellular lysates (40 μg) prepared from one set of transfected cells. The membrane was probed with antibodies against Myc and β actin, as indicated.