Joyce’s work focuses on understanding the mechanisms of tumor metastasis by investigating how the microenvironment responds to metastatic tumor cells and how heterotypic interactions between tumor and stromal cells differ between secondary organ metastasis sites.16 By comparing gene expression array profiles from tumor and stroma cells in micro- and macromestases in the brain, lung, and bone, they identified a protease, cathepsin S, with high specificity for brain metastases. Here, CTSS is linked to neoplasm.