Additionally, while serine/threonine-protein kinase N2 (PKN2) was among the predicted targets for tofacitinib, but not for baricitinib, PKN2-baricitinib binding affinity was previously determined in baricitinib (apparent dissociation constant [Kd app ] = 269 nM and IC50 = 284 nM).( ) Thus, PKN2 was included in the list of targets tested for baricitinib, allowing a direct comparison between tofacitinib and baricitinib inhibitory activity on this target.