“…This level includes in vitro tests such as the CTAs, which may also be at Level 2: The SHE assay can be utilized for the first steps of the multistep carcinogenic process, whilst the Balb 3T3 and C3H10T1/2 CTA assays are designed to address the later steps of a carcinogenic process. At this level, also 3D liver cell models (Hengstler et al, 2015;Prestigiacomo and Suter-Dick, 2015;Ramachandran et al, 2015;van Grunsven, 2015) and isolated organ studies, such as tissue perfusion and histopathology from in vivo repeated dose studies would be relevant.…”