Northern blot analysis of Nix expression. Membranes were prepared using RNA from bone marrow (lane 1), leukocytes (lane 2), reticulocytes (lane 3), K562 cells (lane 4), HeLa cells (lane 5), and Jurkat cells (lane 6). RNA was hybridized with an 850-bp segment of Nix mRNA. Arrows indicate the molecular sizes of 2 bands.