Figure 4

γH2AX frequency mean ± SD after 3 h exposure to WMCS from reference cigarette. [A] 3R4F, [B] M4A. Circle (-●-) represents WMCS results, square (-■-) represents positive control etoposide (1 mM final), triangles (-▼- and -▲-) represents negative controls, air and incubator controls respectively and dotted red line represents the 1.5-fold increase over the air control indicating the threshold of genotoxic response. [C] γH2AX fold-induction for both reference cigarettes 3R4F (blue) and M4A (red), dotted line indicates genotoxic level (>1.5-fold γH2AX response).