Effect of CKβ8-1 and CKβ8 on colony formation by low-density human marrow cells. Low-density human bone marrow cells were plated at 5 × 10⁴ cells/mL with 10% to 30% FBS growth factors, and chemokines (50 ng/mL) in a 0.3% agar or 1% methylcellulose culture medium. Colony formation was scored 14 days after incubation in 5% CO₂ and lowered (5%) O₂. Results are representative of three separate samples. (▨), Control medium; (▩) control diluent; (▧), CKβ8-1; (▩), CKβ8; (▧), MIP-1α.