Rasal2 regulates tumour progression via an exosomal pathway in vitro. (a) MCF-7 cells were cultured with 10 μg of PKH26-labelled exosomes secreted from MCF-7 cells for different times (0, 2, 4, 8, 16, 24-h) and then the cells were observed by confocal microscopy. MCF-7 cells were found to take up autologous exosomes in a time-dependent manner (Scale bar: 20 μm); (b) the internalization of autologous exosomes was also visualized in MDA-MB-231 cells. After 8-h treatment with 10 μg of PKH26-labelled autologous exosomes, the internalization of exosomes was confirmed by confocal microscopy under different magnifications (20×, 40×, 63×) in MCF-7 and MDA-MB-231 cells(Scale bar: 20 μm); (c)–(e) the cell proliferation rate was measured by CCK-8 assay after incubation with different concentrations (0.0125, 0.025, 0.05 μg/μl) of autologous exosomes for 24-h, and the migration and invasion rates were determined by transwell migration assay and matrigel invasion assay after 0.05 μg/μl of CT-exo and KO-exo were co-cultured with autologous cells for 24-h. The findings showed that autologous exosomes regulate diametrically progression of MCF-7 cells and MDA-MA-231 cells (Scale bar: 100 μm); data are presented as the mean ± S.D. (n = 3) *p < 0.05,*** p < 0.001 vs. CT-exo (t-test, two-tailed).