Using this probe, the amount of newly transcribed 47S was quantified in MRC5-SV (wild type cell line), XPCS1RO-SV (immortalized cell line derived from a XP-G/CS patient with a XPG protein containing a frameshift mutation at aa 926 and a premature stop codon at aa 980 [28]), XPCS1RO-SV+XPG-GFP (rescue cell line) cell lines (S1 Fig). Here, ERCC5 is linked to Cowden syndrome 1.