Functional interaction between TBP and CDX1. (A) Lack of activity of CDX1 on the pTGTA-Luc reporter. HepG2 cells were co-transfected with the reporter plasmids pTGTA-Luc and pRL-null, and with the expression plasmids encoding TBP-spm3, HA-CDX1, TBP or with the combination of TBP-spm3 plus CDX1. The data obtained in triplicate ±SD are representative of three independent experiments. (B) Interaction of TBP-spm3 with CDX1. Cells were co-transfected with the plasmid encoding HA-TBP-spm3 and the control vector pBC or the plasmid coding for GST-CDX1. GST-pulldown extracts were analyzed by western blots using anti-GST and anti-HA antibodies, demonstrating the interaction between TBP-spm3 and CDX1. The presence of HA-TBP-spm3 in the cell extracts prior to immunoprecipitation was controlled by western blot using anti-HA antibody (Input). (C) Synergistic effect of TBP-spm3 and CDX1 on the pTGTA-G6Pase-Luc reporter plasmid. HepG2 cells were co-transfected with the reporter plasmids pTGTA-G6Pase-Luc and pRL-null, and with the expression plasmids encoding HA-TBP-spm3, HA-CDX1 or HA-TBP-spm3 plus HA-CDX1. The data obtained in triplicate ±SD are representative of three independent experiments.