FN1 and neoplasm: Our single-cell transcriptome analysis, corroborated by spatial transcriptome analysis, revealed that the presence of Fn impedes the maturation of secretory IgA (sIgA) by disrupting the communication between IgA plasma cells and tumor-associated macrophages (TAMs) involved in IgA induction and dysregulating a co-regulatory gene module essential for sIgA maturation.