Recent reports have suggested that tumors are organized in heterogeneous populations. Within these populations, a small subpopulation of cells is more capable of initiating malignancy; these are called cancer stem cells. In this study, HT-29 cells were sorted according to the presence or absence of the cancer stem cell marker CD133. We confirmed that CD133+ cells possessed higher clonogenicity compared to CD133- cells. Furthermore, proteomic analysis identified 10 proteins, including actin-related protein 2/3 complex subunit 5-like and profilin 2. In conclusion, our data demonstrated that the expression of specific proteins associated with metastasis and invasion in CD133+ cells contributed to the sternness and tumorigenic properties of these cells. (C) 2012 Elsevier Inc. All rights reserved.