Previously, we have described the establishment of a subpopulation of cancer stem cells from the human colorectal carcinoma cell line MIP101. These cells exhibit enhanced clonogenic and tumorigenic capacities. Depletion of the stem compartment in the cancer cell population blocks its tumorigenicity. The present work is dedicated to a comparison of the tumorigenic potential of cell populations with an enriched or depleted stem compartment. We showed that tumor growth after xenografting of an enriched stem cell population can be suppressed by intramuscular injections of ganciclovir. Thus, we suggest an approach to isolating a cell population with high Oct4 promoter expression in the MIP101 colorectal carcinoma line and eliminating these cells from the population in vitro as well as in vivo.