Expression of PTK7 in leukemia cell lines and in normal donor bone marrow. (A) Western blot analysis of leukemic cell lysates using a polyclonal anti-PTK7 antibody. These data were confirmed by flow cytometry using a monoclonal anti-PTK7 PE antibody (B). (C) Flow cytometric data on a normal donor marrow. PTK7⁺ cells are in black, and CD45^dim CD34⁺ CD38⁻ cells are in red. CD45dim CD34⁺ CD38⁻ PTK7⁺ cells represent 65% of this population.