Drug repositioning is an important area of biomedical research. The drug repositioning studies
have shifted to computational approaches. Large-scale perturbation databases, such as the Connectivity
Map and the Library of Integrated Network-Based Cellular Signatures, contain a number of
chemical-induced gene expression profiles and provide great opportunities for computational biology
and drug repositioning. One reason is that the profiles provided by the Connectivity Map and the Library
of Integrated Network-Based Cellular Signatures databases show an overall view of biological mechanism
in drugs, diseases and genes. In this article, we provide a review of the two databases and their recent
applications in drug repositioning.