Status of INK4 locus genes in BLIN-2. DNA was isolated from RAMOS, BLIN-1, and BLIN-2 using TRI reagent and amplified with primers specific for various INK4 locus exons, as described in Materials and Methods. BLIN-2 was separated from BM stromal cells by FACS sorting before DNA isolation. The RAMOS Burkitt lymphoma cell line served as a positive control for amplification of all INK4 locus genes.