An alternative approach is to decompose a compound library based on kinase-focused criteria and recombine the resulting fragments to a kinase-focused molecule library. Recently, Yang et al. reported a ligand-based fragmentation and recombination strategy, which was applied on both a kinase-focused (194 kinase inhibitors from PKIDB ) and a kinase-unfocused library of ∼4.6 million compounds. The fragments were assigned to three different fragment pools representing three designated parts of a kinase inhibitor, i.e. the core, connecting, and modifying fragments. Without using 3D structural information, fragments were assigned to the core fragment pool if a donor-acceptor hinge recognition pattern could be found. Enumerating different combinations of core-connector-modifying fragments yielded two virtual kinase-focused recombined molecule libraries (∼500,000 and ∼40 million recombined molecules), based on the aforementioned kinase-focused and kinase-unfocused input data.