label: ribonucleotidyl-uridine-RNA => a 5'-end dephospho-uridine-RNA + a 3'-end 2',3'-cyclophospho-ribonucleotide-RNA
label_lc: ribonucleotidyl-uridine-rna => a 5'-end dephospho-uridine-rna + a 3'-end 2',3'-cyclophospho-ribonucleotide-rna