Western Blot Quantification Protocol

Cells extraction, lysate quantification, SDS-Page and Western blot were performed as described previously using stainfree gels [22 (link)]. Membranes were incubated with mouse anti-GAPDH (GeneTex, Irvine, CA, USA), mouse anti-pEGFR (Tyr1068, 15A2), mouse anti-BCRP (BXP-21), mouse anti-pHSP27 (Ser82, B-3), mouse anti-HSP27 (F-4), mouse anti-integrin β₄ (A9), rabbit anti-ERK1/2 (Cell Signaling Technology, Frankfurt am Main, Germany), rabbit anti pERK1/2 (Thr202/Tyr204, Cell Signaling Technology) rabbit anti-DDR1 (Cell Signaling Technology), rabbit anti-pDDR1 (Tyr513, Cell Signaling Technology) as well as goat anti-rabbit and anti-mouse IgG kappa binding protein IgG HRP-conjugated diluted in 1% BSA solution. If not indicated otherwise, antibodies were purchased from Santa Cruz Biotechnology. Western blot was quantified via chemiluminescence using Clarity Western ECL substrate chemiluminescence kit (BioRad). Besides the loading control GAPDH, we used stainfree total protein normalization. Membranes were photographed and quantified using ChemiDoc XRS+ imaging acquiring system (BioRad) and Image Lab software v. 6.0 (BioRad). Representative uncut Western blots are shown in Figure S5.