Recombinant NXPH1 directly inhibits colony forming ability and size of primary huCB HPCs. (A) Percent of wells containing individually plated huCB CD34⁺ cells producing CFU-GM, BFU-E, and CFU-GEMM colonies in the presence of recombinant NXPH1, and/or NRXN1α (252 wells were evaluated for each point; mean ± SD). (B) Percent of wells containing individually plated huCB CD34⁺ cells producing CFU-GM, BFU-E, and CFU-GEMM colonies in the presence of recombinant NXPH1 and/or anti-DAG1 blocking Ab (252 wells were evaluated for each point; mean ± SD). (C) Percent of wells containing individually plated huCB CD34⁺ cells grown under a variety of conditions in the presence and absence of recombinant NXPH1-producing CFU-GM colonies (> 500 wells were evaluated for each point; mean ± SD). (D) Size of CFU-GM colonies produced by individually plated huCB CD34⁺ cells grown under a variety of conditions in the presence and absence of recombinant NXPH1 (representative colonies were selected for display). Microphotographs were taken on a Nikon Labophot with a PLAN objective ×10 (NA 0.3) at room temperature. Images were captured using a 5-mega pixel CCD Nikon DS-Fi1 digital camera in conjunction with NIS-Elements D2.30, Sp1 (Build 325). *P < .05, **P < .005, ***P < .0005.