Experimental validation of predicted localization of human proteins. GFP-tagged full-length genes of target proteins and RFP-tagged compartment specific genes were transiently co-expressed in two normal and two breast cancer cell lines. Subcellular localization of the transiently expressed proteins was determined under the confocal microscope (40X). To facilitate the visualization of predicted subcellular localization, the specific RFP-tagged protein marker/dye for each localization was used in colocalization studies. Hoechst (nuclear dye) was used in all experiments. This figure shows a representative observation of colocalization in MCF-7 cells for each of the nine subcellular compartments used for validation in this study.