SHMT1 and malignant colon neoplasm: Figure 4A shows that 2.12 inhibits the total SHMT activity in cancer cell lines in a dose dependent manner and that SHMT activity in lung cancer cells is much more sensitive to compound 2.12 (IC50 between 11.5 and 34 μM) than in colon cancer cells (IC50 between 34 and 200 μM).