Pim-1 phosphorylates Runx proteins in vitro. (A) Bacterially produced GST fusion proteins expressing either full-length (FL) or fragments of Runx1 or Runx3 were incubated with GST-Pim-1 in in vitro kinase assays. The phosphorylation products were separated on SDS-PAGE and visualized by autoradiography. GST alone (-) was used as a negative control. * indicates protein degradation products. (B) Schematic presentation of the functional domains of Runx1, including the Runt domain, an activation domain (AD) with two major transactivation elements (TE1 and TE2), a minor transactivation element (TE3), an inhibitory domain (ID) and the C-terminal VWRPY sequence. Shown are also the fragments phosphorylated by Pim-1 in Runx1 or Runx3, which lacks the sequences corresponding to TE3 of Runx1.