Comparison of CD10/NEP-driven luciferase activity in Nalm-6 and FHTE56 cells cotransfected the alternatively spliced CBF-B/NF-YA cDNAs. Nalm-6 cells (A) or FHTE56 cells (B) were cotransfected with 20 μg wild-type (W) or mutant (M) CD10/NEP (−263/+147) pXP₂ , 40 μg of the CBF-B/NF-YA short pSAS (S) and CBF-B/NF-YA long pSAS (L), and 1 μg of CMV-GH. Luciferase activity was measured 48 hours posttransfection and normalized for GH production. Promoter activity (RLU/ng/mL) represents mean and standard errors for two separate experiments performed in duplicate or triplicate. Nalm 6 cells: W + S 37.1 ± 3.5 (baseline); W + L, 49.5 ± 5.7 (33% increase over baseline, P = .09); M + S 39.7 ± 3.6 (7% increase over baseline, P = NS); M + L 37.0 ± 3.7 (0% difference from baseline, P = NS). FHTE56 cells: W + S 69.1 ± 4.3 (baseline), W + L 101.9 ± 30.8 (47% increase over baseline, P = NS). The differences in CD10/NEP-driven luciferase activity in cells transfected with W + S, W + L, M + S, or M + L were evaluated using a one-sided Student's t-test.