AML: PTK7 is expressed in a subgroup of AMLs. (A) Flow cytometric data using the monoclonal anti-PTK7 antibody. (Top panel) An AML patient with 95% of PTK7⁺ cells. (Bottom panel) An AML patient with a mixed blast population. In this sample, myeloid cells (CD34⁺ CD117⁺) are PTK7⁺, whereas monocytic blasts are PTK7⁻. Of note, these monocytic blasts expressed significant levels of CD11b and CD14 (data not shown). (B) Western blot of fresh AML protein extracts using a polyclonal antibody directed against PTK7. (C) Correlation of PTK7 expression with cytologic findings using the FAB classification: FAB M1, M2, and M6 AMLs frequently express PTK7 compared with FAB M4 or M5 AMLs (Fisher exact test, P < .001).