Effect of MARCO expression in D1 cell morphology. D1 cells were infected with the retroviral expression vector PINCO, encoding the EGFP and MARCO proteins, or the empty PINCO vector, as control, encoding only the EGFP protein. (A) MARCO-transduced cells were analyzed for MARCO expression by flow cytometry after staining with the anti-MARCO mAb or an irrelevant isotype-matched mAb. (Ai) EGFP expression on infected cells. (Aii) MARCO expression on EGFP-positive gated cells. (B) Virally infected cells were stained for filamentous actin (red) 48 hours after infection. Filamentous actin organization of MARCO-transduced D1 cells (C) identified as EGFP positive. (D) Filamentous actin organization of D1 cells infected with the empty retroviral vector (E) encoding only EGFP. Original magnification, × 600. (F) Percentage of MARCO-expressing or control cells showing a round morphology. A total of 400 cells were counted in randomly selected fields. The experiment was repeated 3 times with similar results. Error bars indicate SD.