Immunofluorescent Staining: Either the TK-1 cell line (LPAM-1 expressing) or the 18-81 MuLV-transformed pre-B cell line (LPAM-1 negative) was labeled with Rat anti-Mouse LPAM-1 and then stained with Goat anti-Rat IgG-FITC. The primary cell populations on each scatter plot were then gated and analyzed by flow cytometry. Amount Used: 1 Ã?ug/10e6 cells.