Recombinant NXPH1 inhibits colony forming ability of muBM HPCs. (A) Percent recombinant NXPH1-mediated inhibition of CFU-GM colony formation in primary muBM cells plated as a population under a variety of factor-stimulated growth conditions (3 combined independent experiments, each done in triplicate; mean ± SD). (Bi) Representative Western blot of lysate from primary muBM cells cultured for 24 hours under a variety of conditions. The first lane represents lysate from freshly harvested muBM. β-actin is shown as a loading control. (ii) Densitometric analysis of NRXN1α expression in Western blots. Values were normalized to β-actin and represented as a percent of the day 0 control (4 combined independent experiments; mean ± SD). (C) Calculated dose-response curves modeling the NXPH1-mediated inhibition of CFU-GM colony formation in the presence of GM-CSF + SCF. HPCs were derived from either individually plated huCB CD34⁺ (R² = 0.95), huLDCB plated in population (1 × 10⁴cells/mL; R² = 0.99), or muBM plated in population (5 × 10⁴cells/mL; R² = 0.99; 288 wells were evaluated for each data point in experiments involving a single plated cell; at least 3 independent experiments performed in triplicate were used for calculating data points involving cells plated in a population; mean ± SD). *P < .05, **P < .005, ***P < .0005.