Crk shRNA xQund5 NSP5 loxP Zif268 antisense ZFNs rapamycin WUS Banksiinae recombinase perforin RPIX exonic Bechen oligonucleotides downregulate nuclease CXCL16 siRNAs chemokine PGCs polyA TSP1 mRNAs RNAa USP7 Introns mRNA Hh synemin PTCH1 calpains immunoreceptor epitope ingression transposon