PTBP1 and sarcoma: We then tested for additional well-established RBPs (Fig. 1f), namely polypyrimidine tract binding protein 1 (PTBP1), fused in sarcoma (FUS), and the more recently identified RNA-binding enzymes glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and enolase (Eno1);3 all of which are enriched by PTex in a UV-irradiation-dependent manner whereas the highly abundant DNA-binding histone H3 is depleted.