HIF-1α is transcriptionally upregulated in CLL cells upon coculture with stromal cells. (A-C) Relative expression of HIF-1α after 24 hours of coculture with Hs5 cells as compared with cells cultured without stroma. (A) MEC-1 cells. Data represent mean values ± SEM of 3 independent experiments. (B) Leukemic murine cells (CD5⁺CD19⁺) from PB of EµTCL1-transplanted mice. Data represent mean values ± SEM of 2 independent experiments. (C) Primary CLL B cells. Data represent mean values ± SEM (n = 10). (D-E) Relative expression of the indicated genes in MEC-1 cells (D) and primary CLL B cells (E) after 24 hours of coculture with Hs5 cells as compared with cells cultured without stroma. Data represent mean values ± SEM of 3 independent experiments (D) and mean values ± SEM (n = 10) (E). (F) Percentage of annexin V⁺ primary CLL B cells (CD19⁺) after 72 hours of culture or coculture with CLL lymph node stromal cells (LNS1) (n = 5). (G) Relative expression of HIF-1α in primary CLL B cells after 24 hours of coculture with LNS1 as compared with cells cultured without stroma (n = 9). (H) Relative expression of the indicated genes in primary CLL B cells after 24 hours of coculture with LNS1 cells as compared with cells cultured without stroma (n = 9).