CD44ICD rescues the fusion of macrophages treated with DAPT. (A) Rat alveolar macrophages were transduced with MigR1 empty or encoding CD44FL, CD44ΔE, or CD44ICD, and treated or not with DAPT (10 μM) for 4 days (bar represents 2 mm; ^*P < .01 versus MigR1; SD; n = 6). (B) Cells from panel A were subjected to Western blotting analysis using an mAb directed against myc. Overexposed blots revealed CD44ICD in CD44FL- and CD44ΔE-transduced cells, but not in the presence of DAPT.