IRF4 and neoplasm: To determine the specific lineages and stages of tumor cells, we performed scRNA-seq analysis for one normal sample from Tg(lck:mCherry) at 3 months old (“control”), five non-tumor preleukemic samples from Tg(lck:IRF4;p53wt/wt) at 3 months old (“PIRF4”), three early-stage and six late-stage tumor samples from Tg(lck:IRF4;p53wt/wt) (“EIRF4” and “LIRF4”), and five late-stage tumor samples from Tg(lck:IRF4;p53wt/mut) fish (“LMUT”) (Fig. 3A).