BRAF inhibition causes resilience of melanoma cell lines by inducing the secretion of FGF1

a Conditioned supernatant (cond. SN) was generated from melanoma cells treated for 3 days with vemurafenib (vem, 0.5？μM) and from DMSO-treated control cells (ctrl). Donor cells were seeded to achieve an equal confluency at day 3. After excessive washing with PBS, donor cells were starved over night with medium containing 2% dialysed FCS. The following day, acceptor cells (which were starved for 3 days) were treated with filtered conditioned supernatant for 48？h followed by MTT measurement. b Western blot showing P-ERK1/2 (Thr202/Tyr204) of UACC-62 cells treated for 3 days with indicated concentrations of vemurafenib. Actin served as loading control. c MTT assays of the melanoma cell lines M14, UACC62, A375 and the fibroblast cell line WI-38 treated for 48？h with DMSO (“ctrl SN”) and vemurafenib-conditioned supernatant (“vem SN”). mel: melanoma; fb: fibroblast. Data are derived from three independent experiments. *p？<？0.05; **p？<？0.01; ***p？<？0.001 (Student’s t-test, unpaired, comparison between vemurafenib-conditioned and control conditioned supernatant, which was set as 100%