Effects of IL-8 and NAP-2 on the viability of normal human bone marrow cells (A) and on the sensitivity of the cells to 5-FU (B). Cells (2 × 10⁶/mL) were preincubated with IL-8 or NAP-2 for 48 hours. 5-FU (1 μg/mL) was then added respectively for an additional 24 hours. Cell viability was measured with an MTT assay. *P < .05 v control cells.