BCL2 and idiopathic pulmonary fibrosis: In vitro studies by ourselves and others have shown that fibrotic lung fibroblasts isolated from patients with IPF are resistant to apoptosis through decreased expression of the death receptor Fas and concurrent increased expression of antiapoptotic genes, including B cell lymphoma 2 (BCL-2), PTPN13, and XIAP (6, 9, 10), which together impair apoptotic signaling (6–8, 11–13).