Figure 3: Efficacy of Vandetanib in the RTE Cell Transformation. Primary RTE cells were treated with B[a]P alone or with five half - log concentrations (0.003, 0.01, 0.03, 0.1 and 0.3 µM ) of Vandetanib. On day 30, the culture dishes were fixed and stained for scoring of transformed foci (A). Transformation frequency was determined by scoring transformed foci (type II & III) and the results are expressed as percent inhibition of transformation in B[a]P + Vandetanib- treated versus untreated B[a]P control (B). As the lowest concentration of Vandetanib on B[a]P-induced transformation showed more than 50% inhibition, the IC50 value is considered to be <0.003 µM (C).