CBX5 and myeloid sarcoma: Previously, we have explored this possibility by examining the activity of HP1α/CBX5, a transcriptional repressor with affinity for both chromatin and RNA (4, 5, 6), and encoded by a gene sharing one of its promoters with hnRNPA1, a gene harboring single nucleotide polymorphisms (SNPs) previously associated with an elevated risk of MS (7).