Fig. 2

The absence of integrin α3 promotes HER2-dependent tumor growth and vascularization. a Survival Kaplan-Meier plots comparing Itga3 KO and WT mice. The median age when half of the mice per group needed to be sacrificed was 180 days for Itga3 KO mice and a month later (212 days) for Itga3 WT mice (n = 17). b Itga3 KO mice developed significantly bigger tumors from the age of 21 weeks on (n = 17; unpaired t test, *P < 0.05, **P < 0.005). c No difference in the number of proliferating Ki67-positive tumor cells was observed between Itga3 KO and WT mice. Left—Ki67-positive cells were counted in five fields of randomly selected tumors from eight mice per genotype (unpaired t test, P = 0.7168). Right—representative tumor images of immunohistochemical staining for Ki67. d, e Plots showing the fitted linear regression of average tumor sizes during d first and e last 3 weeks of tumor growth per mouse. The slopes of trend lines are significantly different during the first weeks of tumorigenesis, showing an increased growth rate in Itga3 KO mice. Such difference is not observed during the last 3 weeks of tumor growth before mice were sacrificed (n = 17, unpaired t test, *P < 0.05). f Vascularity of tumors, quantified as integrated density of CD31 stained samples (left), was increased in Itga3 KO mice. Five fields of randomly selected tumors from nine WT and ten KO mice were analyzed (unpaired t test, P = 0.0176). Right—representative tumor images of immunohistochemical staining for CD31