Quod erat demonstrandum? No restriction endonuclease fold in MIF

It was claimed in a recently published article that MIF functions as an exo/endo-DNase mediating cell-death upon being induced by DNA damage and PARP1. MIF, for which tautomerase activity has been previously reported, is a member of the tautomerase superfamily which does not feature nucleases. The central premise of the authors to suggest that MIF functions as a DNase is the supposed structural relationship to nucleases of the Restriction endonuclease (REase) fold, which frequently but not always contain a motif of the form PD-(D/E)XK. However, we present evidence to show that this claim is entirely unsupported.