IRAK4 and myeloid neoplasm: Importantly, somatic mutations of U2AF1 that occur in 10–15% of patients with PMF cause alternate splicing of IRAK4 gene transcripts to yield a longer isoform retaining exon 4, encoding a protein, IRAK4-Long (L) that is oncogenic in myeloid malignancies and can alone drive proliferation of the malignant clone through sustained myddosome activation [80].