Reconstitution of donor FLC in to mature macrophages in bone marrow chimera mice. (A) Sixty days after FLC transplantation, genomic DNA from alveolar macrophages from resulting chimera mice was subjected to Southern hybridization as described in “Methods.” The hybridization signals in WT (8.3 kb), PU/ER(T)^+/− (8.3 and 5.6 kb), and PU/ER(T)^+/+ (5.6 kb) indicated the genotype of the resulting chimera mice. (B) Alveolar macrophages from the WT, PU/ER(T)^+/−, and PU/ER(T)^+/+ bone marrow chimera mice were collected before and after clearance (45th and 55th day) of circulating tamoxifen. Cells were analyzed by FACS for Annexin V/F4/80 and propidium iodide (PI) binding to assess cell apoptosis.