Involvement of the APC/EPCR/Par-1 pathway in the maintenance of EPCR⁺ HSCs. (A) Both LSK/EPCR⁺ and LSK/EPCR⁻ cells expressed the mRNA of Par-1 (F2r), but not of TM (Thbd). (B) In E12.5 mouse FL, TM-expressing cells (green) shown at asterisk and APC formation (red) were visualized using immunohistochemistry. (C-F) LSK/EPCR⁺ or LSK/EPCR⁻ cells were cultured for 2 days in the presence of APC supplementation. The APC supplement did not affect cell proliferation in either LSK/EPCR⁺ or LSK/EPCR⁻ cells (C-D); however, it significantly suppressed the number of dead cells among the LSK/EPCR⁺ population (E). Error bars represent SD (n = 3). *P < .05.