Vector maps. Abbreviations: 5’ and 3’ mir, 5’ and 3’ flanking sequences derived from the murine mir-155 micro-RNA gene; Bsr, blasticidin resistance gene; DRE, DsRed express; EGFP, enhanced green fluorescent protein; Gluc, (secreted) Gaussia luciferase; HIV RRE, human immunodeficiency virus rev response element; IRES EMV, encephalomyelocarditis virus internal ribosome entry site; lacZα, gene encoding the alpha-fragment of E. coli β-galactosidase gene; LTR, retro/lentiviral long terminal repeat; PAC, puromycin resistance gene; PL, polylinker. Unique sites 5’-EcoRI, XhoI, ApaI, MluI, NotI, XbaI, SpeI, BamHI, SmaI, PstI-3’; PPGK, phosphoglycerate kinase promoter; PCMV, CMV promoter; PSV40, SV40 promoter; PTet, doxycycline-regulated promoter; rtTA, reverse tetracycline-controlled transactivator protein; wPRE, woodchuck hepatitis virus posttranscriptional regulatory element.