BPIFA1 and neoplasm: Notably, the second route was also partly shared by a subpopulation of Club cells in cluster 4 that showed a Goblet-like gene signature (upregulated Ltf, Bpifa1, Bpifb1, Reg3g expression), and differentiated into cluster 11 (Supplementary Data 3), retaining the expression of Ltf. Our results show that although different tumour clusters arise on diverse paths, these paths are interconnected.