Self- and auto-regulated AAV type 2-based expression of fluorescent proteins. (A) Schematic representation of an auto-regulated (pDF124), a bidirectional (pDF89) and a self-regulated (pDF141) AAV type 2-based expression unit. (B) Fluorescence micrographs of human fibrosarcoma cells (HT-1080) and a human breast cancer cell line (MCF-7) transduced with pDF124-, pDF89- and pDF141-derived AAV particles (2000 genomic particles/cell) cultivated in the presence (+) and absence (-) of EM. (C) FACS-mediated quantification of EYFP in HT-1080 transduced with equal amounts of viral particles (2000 genomic particles/cell) and cultivated in the presence (+EM) and absence (-EM) of erythromycin. Abbreviations: EM, erythromycin; ET1, erythromycin-dependent transactivator; ETR, ET1-specific operator; EYFP, enhanced yellow fluorescent protein; IRES, internal ribosome entry site; ITR, inverted terminal repeat; pAI, synthetic polyadenylation signal; pASV40, simian virus 40 polyadenylation signal; PETR, erythromycin-responsive promoter; PHSP70min, minimal version of the Drosophila melanogaster heat-shock protein 70 promoter; PSV40, simian virus 40 promoter.