PPI network connecting proteins used in the HTS-Y2H assays in the present study. Part of the network around the RXRA/NRIP1 and CDK2/CDKN1A interactions is enlarged in the upper frame. Proteins are represented as diamonds (targets of drugs approved by FDA) and circles (non-targets of FDA-approved drugs). The information on target proteins of FDA-approved drugs was obtained from the DrugBank database . RXRA, NRIP1, CDK2, and CDKN1A are colored yellow. Proteins related to OMIM  diseases are colored brown and the remaining proteins are grey. Interactions between proteins are indicated by lines. Novel PPIs detected in this study are shown in red, and those retrieved form a public database, HPRD , are in blue. PPIs are colored green if the interaction was detected in the present study and also retrieved from the HPRD. The network was drawn using the program Cytoscape (version 2.3.2) . See Additional file 4 for the original and larger version of the PPI network.