The kinase activities of GST fusion proteins were measured <i>in vitro</i>.

<p><b>A.</b> Phosphorylation activities of GST fusion proteins containing full-length Stk (using plasmid pQG77), Stk<sup>1–263</sup> (pQG78) or Stk<sup>40–263</sup>(pQG79) were measured with a Kinase-Glo™ luminescent kinase assay <i>in vitro</i> at 32°C for 4 h. <b>B.</b> Phosphorylation activities of GST fusion proteins containing full-length Stk (using plasmid pQG77) were measured with a Kinase-Glo™ luminescent kinase assay with or without staurosporine <i>in vitro</i> at 32°C for 4 h. GST was used as a negative control. RLU, relative luminescent unit. Data are derived from three independent experiments, **, P<0.01; ***, P<0.001 (versus GST).</p>