Because CXCR4/CXCL12 interaction is important for development of bleomycin-induced PF through recruitment of BM-derived progenitor cells [4,5,7], we investigated whether it is also critically involved in radiation-induced PF and whether blocking CXCR4 with our novel compound, MSX-122, can alleviate this process. This evidence concerns the gene CXCR4 and pemphigus foliaceus.