We next evaluated the antitumour efficacy of nintedanib in vitro and found that it did not attenuate the viability of B16-F10 cells or that of A549 human lung adenocarcinoma cells (examined as a negative control) at concentrations up to 1 μM (Fig. 1b).22 Nintedanib did attenuate the viability of H1703 human lung squamous cell carcinoma cells (Fig. 1b), which served as a positive control on the basis of the previous detection of FGFR1 and PDGFRA amplification in these cells22,23 and of our finding that they express PDGFR-α and FGFR-2 (Supplementary Fig. 2). The gene discussed is PDGFRA; the disease is squamous cell lung carcinoma.