In eukaryotes, protein phosphorylation of serine, threonine or tyrosine residues 
by protein kinases plays an important role in many cellular processes. Members 
of the protein kinase CK1 family usually phosphorylate residues of serine that 
are close to other phosphoserine in a consensus motif of pS-X-X-S, and they are 
implicated in the regulation of a variety of physiological processes as well as 
in pathologies like cancer and Alzheimer's disease. Using a structure-based 
virtual screening (SBVS) approach we have identified two anthraquinones as novel 
CK1delta inhibitors. These amino-anthraquinone analogs (derivatives 1 and 2) are 
among the most potent and selective CK1delta inhibitors known today (IC(50)=0.3 
and 0.6 microM, respectively).