SNORA42 was cloned as described previously.21 (link) A pCDH vector (System biosciences, Mountain view, CA, USA) was used for ectopic over-expression of SNORA42. The pCDH vector encoding intact sequence of SNORA42 cDNA or empty vector as a control was infected into HEK293T cells together with pPACKH1 Packaging Plasmid mix (System biosciences) for producing viral particles using Lipofectamine 2000 (Invitrogen, Carlsbad, CA). Further information is provided in the Supplementary material and methods.