. "The chemical reactions and pathways resulting in the breakdown of the mRNA transcript body that occurs when the 5' end is not protected by a 5'-cap; degradation proceeds in the 5' to 3' direction." . . "nuclear-transcribed mRNA catabolic process, exonucleolytic, 5'-3'" . "5'-3' exonucleolytic nuclear-transcribed mRNA catabolic process" . . . .