RBM10-induced exon inclusions of ECM and cytoskeletal transcripts govern metastatic propensity in vivo. (A) Scheme of Hras^G12V/Rbm10^flox mouse thyroid cancer lung metastasis–derived cell line (64860M) and phenotype rescue experiments by Rbm10 re-expression or isoform-specific KD of Vcl (sh.Vcl_Ex19), Cd44 (sh.Cd44_Ex8), and Tnc (sh.Tnc_Ex14); illustration by Biorender. (B) Western blot of 64860M cells expressing empty vector (pLVX) and Rbm10. (C) Mean cell migration velocity by time-lapse imaging in 64860M cells ± Rbm10. (D) Transwell matrigel invasion assay in 64860M cells ± Rbm10. (E) Effect of Rbm10 expression in Luc+ 64860M cells on lung bioluminescence quantification 2 wk after TV injection. (F) Effect of Rbm10 expression on number of mice with lung metastases assessed by lung H&E, 3–4 wk after orthotopic implantation of Luc+ 64860M cells into the thyroid; P value by two-sided Fisher’s exact t test (P = 0.035). (G) Bioluminescence imaging and quantitation of TV-injected Luc+ 64860M cells with or without dual and triple isoform-specific KD of Vcl (Vcl_Ex19), Cd44 (Cd44_Ex8), and Tnc (Tnc_Ex14); P value by unpaired t test versus sh.Scr. (H) Vcl, Cd44, and Tnc dual isoform-specific KDs in 64860M cells show decreased cell migration velocity compared with sh-Scr–transfected cells; P value by unpaired t test versus sh.Scr. (I and J) Decreased Rac1-GTP levels (I) and Rac1 downstream signaling (J) in 64860M cells expressing Rbm10. (K) Isoform-specific triple KD of Vcl, Cd44, and Tnc (sh.3KD) show decreased Rac1-GTP and downstream signaling. Statistical difference was analyzed using unpaired t test (C–E, G, and H) and is indicated as *P < 0.05, and ***P < 0.0001; ns: not significant. sh-Scr; sh.Scramble. Source data are available for this figure: SourceData F4.