A study sponsored by the ECVAM evaluated the reproducibility (between-laboratory and within-laboratory variability) and the predictive capacity of two in vitro cellular systems—the Caco-2/ATCC parental cell line and the Caco-2/TC7 clone—at estimating the oral fraction absorbed (Fa) in humans (Prieto et al., 2010). The study concluded that good estimations of human Fa for five well-absorbed compounds was demonstrated; while moderately and poorly absorbed compounds were overestimated.