This residual staining with anti-CXCL12 antibody reflected decreased amounts of the CXCL12–KRT19 heterodimer (SI Appendix, Fig. S10B), despite an absence of TGM2 protein in the tumors formed with PDA cells lacking TGM2 expression in the TGM2-KO host (SI Appendix, Fig. S10C). The gene discussed is KRT19; the disease is Patent ductus arteriosus.