No detectable expression of transactivator and target gene. PCR on cDNA from bone (lanes 2-9 and lanes 11-13) and aorta (lane 10) was performed with primer pairs specific for the reverse transactivator. Respective genetic background is indicated for bi-transgenic tetop-LAG608G+;α1p-rtTA+ mice. No-reverse transcriptase cDNA sample (lane 11), no-template control (lane 12) and increasing concentrations of genomic DNA template (1, 10, 20, and 50 ng in lanes 14-17, respectively) were included as controls for the PCR assay. PCR on a RNA sample from bone (100 ng of total RNA was used as template for the PCR, lane 18) indicated that there was no significant genomic DNA contamination. Lane 1 is a 100-bp ladder (Invitrogen). Presence and absence of transgene are indicated by + and -, respectively. LA, human lamin A, 276 base pairs; LAdel150, progerin, 123 base pairs. RT-PCR for β-actin served as a control for the RT.