According to our findings, Snail-overexpressing HT-29 cells that imitate to have phenotype of colon cancer cells in the early stage of the EMT showed an increase in the expression and pericellular activity of cathepsin B. It appears that the pericellular localization of cathepsin B, as observed in cancer cells, plays a key role in its function. The gene discussed is SNAI1; the disease is cancer.