CXCR4 and pemphigus foliaceus: Ding et al. [74] reported the development of a multimeric complex based on CXCR4 inhibition of poly(ethylimine) derivatives (PEI-C) for lung delivery of siRNA to silence fibrinogen activator inhibitor-1 (siPAI-1) in a combination therapy for PF, with fluorescence showing the longest drug retention time in the lung, significant downregulation of PAI-1 expression, and significant reduction in intrapulmonary collagen deposition.