NRG1 and neoplasm: Importantly, simultaneous analysis of the distribution of Nrg1 and TGFα protein and mRNA by fluorescent in situ hybridization-immunofluorescence (FISH-IF) revealed excellent concordance, suggesting that the patterns of ligand distribution are mostly due to autocrine expression and that diffusion of the secreted ligands in the tumor tissue has minimal impact on these patterns (Supplementary Fig. 9B, C).