CXCL1 and carcinoid tumor: In particular, the expression of all β-chemokines (including CCL2, CCL7, CCL19, CCL21, CCL22, known to attract monocytes and dendritic cells)20 (Supplementary Data 6), and all CXC chemokines (such as IL8, CXCL1, CXCL3, and CXCL5, known to attract neutrophils)21, were positively correlated with MOFA LNEN LF1 (separating pulmonary carcinoids from LCNEC) and negatively correlated with MOFA LNET LF2 (separating clusters Carcinoid A1 and A2).