JAK1 and neoplasm: Subsequent flow cytometric analyses revealed that adoptively transferred Pmel-1 CD8+ T cells represented a much larger subpopulation of tumour-infiltrating immune cells when compared to adoptively transferred TRP-1 CD4+ T cells, both in HCmel12 CRISPR-ctrl and HCmel12 Jak1-KO tumours, consistent with their differential in vivo expansion dynamics.