In the present paper, we investigated the expression of TST, MPST, CTH, and CBS in the different types of human leukemia cell lines: B-ALL (REH cells), T-ALL (DND-41 and MOLT-4 cells), AML (MV4-11 and MOLM-14 cells), and CML (K562 cells). The gene discussed is CBS; the disease is acute lymphoblastic leukemia.