Schematic representation of the retrovirus vector constructs. Genes of Hyg
R
, EGFP, and rtTA2
s
M2 in all vectors were expressed under the control of LTR, TREtight, and
PGK promoters, respectively. LTR, long terminal repeat; Hyg
R
, hygromycin B-resistant gene; TRE, tetracycline response element; GFP, green fluorescent protein gene; RSV,
Rous sarcoma virus promoter; rtTA2
s
M, reverse tetracycline transactivator; WPRE, woodchuck hepatitis virus post-transcriptional regulatory element. The approximate
positions of the probe for Southern blotting and of the PCR primer set for the detection of theGFPgene sequence are indicated above the vector. Drawings are not to scale.