Fig. 4

Effect of F11R/JAM-A-derived peptide (P4D) on cell viability measured by MTT assay. The cells were untreated (Ctrl), treated with the control scrambled peptide (Scr) or with the F11R/JAM-A antagonistic peptide (P4D) at a concentration of 500 μM. Shapiro–Wilk normality W test has shown that the data do not fall upon Gaussian distribution: EA.hy926–failed (P-values for Ctrl: 0.3657, for Scr: 0.0009, for P4D: < 0.0001); HMEC-1–failed (P-values for Ctrl: 0.1067, for Scr: 0.6482, for P4D: 0.0072); for MDA-MB-231–failed (P-values for Ctrl: 0.0022, for Scr: 0.0042, for P4D: 0.0113). Thus, the data were analyzed by non-parametric Kruskal–Wallis test followed, where applicable, by Dunn’s multiple comparisons test. The differences between tested groups were statistically significant in the case of EA.hy926 cells (P = 0.0041). The post-hoc test has not revealed significant differences for Ctrl vs. Scr (P = 0.1091) and for Ctrl vs. P4D P = 0.7106. The difference was significant for Scr vs. P4D (P = 0.0032). For HMEC-1 cells the differences between the tested groups were statistically insignificant (P = 0.2281). The statistically significant differences between the tested groups were noted for MDA-MB-231 cells (P < 0.0001). The post-hoc Dunn’s multiple comparisons test has shown, that the differences CTRL vs. Scr and Scr vs. P4D were not statistically significant (P = 0.0526; and P = 0.1002; respectively), while the significant difference was found for Ctrl vs. P4D (P < 0.0001)