Physical interaction between C/EBPβ and GATA-1 in vitro. ³⁵S-labeled full-length C/EBPβ was synthesized by translation in vitro and incubated with GST alone (lane 2) or GST-hGATA-1 (lane 3) adsorbed to glutathione-Sepharose, after which the matrix was washed and bound proteins were analyzed as described in Materials and Methods. Lane 1 represents 15% of the amount of labeled protein incubated with matrices.