Expression of FLAG-tagged HOX A5 in K562 cells. K562 cells were transfected with FLAG-tagged HOX A5 (pFAT), empty vector (pCMV-thy-1), or no vector (mock). Cells were purified via cell surface expression of the transfection marker, murine Thy 1.2. Lanes labeled “FT1” and “FT2” represent cell extracts from the flow-through fraction of the two affinity columns used to select Thy 1.2-positive cells; lanes labeled “Thy 1.2+” are cell extracts from the Thy 1.2-positive eluates from the columns; and the lane labeled “FLAG-BAP” is FLAG-tagged bacterial alkaline phosphatase (Eastman Kodak) used as a positve control for the anti-FLAG Western antibody.