PTPRJ and breast cancer: Loss of hetreozygosity (LOH) studies have implicated the protein tyrosine phosphatase receptor J (PTPRJ, DEP-1, PTP-η, CD148) gene in the development of human meningioma [1], colon, lung and breast cancers, and quantitative trait analysis in mouse identified the mouse Ptprj orthologue as the sole candidate gene for the murine colon cancer susceptibility locus (Scc1) [2].