a, Cells were grown in presence (ON) or absence (OFF) of doxycycline or treated with AZD8330 (100 nM) for 16–18 h. Top, ARF6 activity was measured with GGA3–PBD pull-down assay. Bar graph, ARF6 activity was calculated as ratio of captured ARF6:input ARF6/vinculin. b, iKras* p53L/+ tumour cells were grown in the presence (ON) or absence (OFF) of doxycycline, or treated with AZD8330 (100 nM) for 16–18 h. Cell lysates were used for measurement of PIPK activity (n = 3 biological replicates; data are mean ± s.d.). P values were determined by unpaired two-sided Student’s t-test. c, Representative images of morphology change in iKras* p53L/+ tumour cells with dominant negative ARF6 (ARF6(T27N)) or constitutively active ARF6 (ARF6(Q67L)). Experiments were repeated three times with similar results. d, Top and middle, iKras* p53L/+ tumour cells stably expressing ARF6(Q67L) or empty vector were grown in the presence (ON) or absence (OFF) of doxycycline for 48 h and surface SDC1 was measured by FACS using anti-SDC1 antibody. Bottom, fluorescence intensity of surface SDC1 (n = 3 biological replicates; data are mean ± s.d.). P values were determined by paired two-sided Student’s t-test. e, iKras* p53L/+ tumour cells stably expressing ARF6(T27N) or empty vector were grown in the presence (ON) or absence (OFF) of doxycycline for 48 h and surface SDC1 was measured by FACS using anti-SDC1 antibody. Representative histograms (top and middle) and bar chart (bottom) of fluorescence intensity are shown (n = 4 biological replicates; data are mean ± s.d.). P values were determined by paired two-sided Student’s t-test. f, mRNA expression of ARF6 GTPase-activating proteins and guanine nucleotide exchange factors in a iKras* p53L/+ tumour cell microarray dataset on KRAS(G12D) inactivation (n = 4 biological replicates). P values were determined by unpaired two-sided Student’s t-test. g, iKras* p53L/+ tumour cells were grown in the presence (ON) or absence (OFF) of doxycycline or treated with AZD8330 (50 nM) for 16–18 h, and Psd4 mRNA level was measured by RT–qPCR (n = 3). P values were determined by unpaired two-sided Student’s t-test. h, MiaPaCa2 cells containing doxycycline-inducible shRNA targeting human KRAS were grown in the absence (OFF) or presence (ON) of doxycycline, or treated with trametinib (50 nM), AZD8330 (50 nM) or BKM120 (100 nM) for 18 h. Cell lysates were blotted for PSD4, phospho-ERK and KRAS. Arrow, PSD4 band. Experiments were repeated twice with similar results. i, iKras* p53L/+ tumour cells stably expressing Psd4 or empty vector were grown in the presence (ON) or absence (OFF) of doxycycline for 48 h. ARF6 activity was measured by GGA3–PBD pull-down assay. Input lysates were immunoblotted to validate expression of ARF6, p-ERK, p-MEK, PSD4 and KRAS. Experiments were repeated twice with similar results. j, iKras* p53L/+ tumour cells stably expressing Psd4 or empty vector were grown in the presence (ON) or absence (OFF) of doxycycline for 48 h and surface SDC1 was measured by FACS using anti-SDC1 antibody. Representative histograms of FACS analysis (top) and bar graph of fluorescence intensity (bottom) of surface SDC1 are shown (n = 3 biological replicates; data are mean ± s.d.). P values were determined by paired two-sided Student’s t-test. Source data