Inhibition of protein tyrosine phosphorylation blocks Mø ingestion of apoptotic thymocytes. Resident PMø (open circles) and AMø (closed squares) from normal C57BL/6 mice (2 × 105 cell in 400 μl) were pre-incubated with various concentration of herbimycin A (A, B) or genistein (C, D) for 30 min at 37°C, were co-incubated with apoptotic thymocytes in the same concentration of the inhibitor for 90 minutes, and then were assayed for phagocytosis. Data are percentage phagocytosis positive Mø (A, C) and phagocytic index (B, D) as mean ± SEM of at least three replicates in a single experiment.