Suppresses tumor cell growth, migration, angiogenesis, and metastasis in melanoma, osteosarcoma, and breast cancer; inhibits neural stem cell differentiation; inhibits ES cell self-renewal but promotes trophoblast stem cell self-renewal and commitment; suppresses the numbers of hematopoietic stem cells in the bone marrow and spleen; glioblastoma and neuroblastoma CSCs produce high levels of decorin to acquire temozolomide resistance and a quiescent phenotype. The gene discussed is DCN; the disease is breast cancer.