sentence: To facilitate these studies , we gene edited the parental HeLa cell line using the CRISPR-Cas9 methodology to incorporate GFP tags at either the C terminus ( NOC4L , LTV1 ) or the N terminus ( RRP12 ) of RBFs present in the No1 ( NOC4L ) , No1 / No2 / Nuc ( RRP12 ) , and No2 / Nuc / Cyt ( LTV1 ) particle maturation stages ( Supplementary Fig. 3 ) .