The gene expression of a list of 421 gene ontology (GO) splicing factors (https://www.uniprot.org) was verified in immune cells based on scRNASeq data from non-malignant cells of HNSCC primary tumors5, as performed for the splicing genes SRSF1, SRSF2, SRSF3, SRSF5, and TRA2A. From the 421, 41 GO splicing genes were significantly down- or upregulated in immune populations from pN+ when compared to pN0 (adjusted p ≤ 0.05; two-sided Wilcoxon test and Benjamini-Hochberg correction) (Fig. 5c; Supplementary Data 6-1). This evidence concerns the gene TRA2A and head and neck squamous cell carcinoma.