Fig. 2From: Absence of in vivo mutagenicity of multi-walled carbon nanotubes in single intratracheal instillation study using F344 gpt delta rats gpt mutant frequencies in the lung. Four weeks after the treatments, the rats were sacrificed, and their lung samples were collected and analyzed by the gpt assay. Each treated group is shown under the bars. The data are the mean ± SD. *p < 0.05 compared to the controlBack to article page