Analyses of kd/kd-derived EC in vitro. (A) A coculture assay was performed using MSS31 (positive control) and kd/kd spleen-derived stromal cells (kd#1, kd#3, kd#10). The photographs represent benzidine-stained erythroid colonies developed on stromal cells. The number of benzidine-positive colonies consisting of more than 200 cells was scored in each well, and the average of colony number in triplicate wells for each stromal cell line is shown (**P < .01). (B) ECs were harvested from WT and kd/kd (kd) BM and spleens (SP). The mRNA expressions of adhesion molecules and endothelial receptors were examined by quantitative RT-PCR. The expression levels seen in WT BM were normalized to a value of 1 as the standard. ■ represents WT; □ represents kd/kd (*P < .05, **P < .01, compared with WT). (C) kd/kd spleen-derived stromal cells (□ represent kd#1, kd#3, kd#10) and MSS31 cells (■) were analyzed for the mRNA expression of adhesion molecules and endothelial receptors by quantitative RT-PCR. The expression levels seen in kd#1 cells were normalized to a value of 1 as the standard (*P < .05, **P < .01, compared with values from MSS31). Error bars represent SD.