5-UTR mRNA splicing determines CD20 levels

In this issue of Blood, Ang et al(1) show that human CD20 messenger RNA (mRNA) undergoes alternative splicing to generate distinct 5' untranslated region (5'-UTR) variants, which determine the cell-surface CD20 levels in malignant B cells and the interpatient variability in the expression of this therapeutic target. These variants can also be used as an escape mechanism from anti-CD20 therapies.