P190B transgene enhances cell-ECM adhesion, invasion, and metastasis. (a) Exogenous p190B expression does not alter the histopathology of MMTV-Neu lung metastases, which resemble undifferentiated adenocarcinomas that are typical of MMTV-Neu mice. (b) Average number of metastases per mouse at tumor burden was determined by counting metastatic lesions in serial sections of the entire lung. rtTA/Neu control mice had similar numbers of metastases as TetO/Neu mice (data not shown). ANOVA was used to determine statistical significance between the groups. Error bars represent standard error of the mean. (c) P190B (black bars) and rtTA (gray bars) primary MECs were analyzed for their ability to adhere to ECM proteins. An MTS assay was used as an indirect measurement of the number of adherent cells. Data represent three independent experiments. A t test was used to determine statistical significance and error bars represent standard errors of the mean. (d) Exogenous p190B expression promotes invasion as determined by confocal microscopic analysis of p190B and rtTA primary MECs cultured in Matrigel for 12 days and immunostained to detect red = p190B, green =αtubulin, blue = DNA. Arrows indicate invasive projections. (e) The number of invasive structures was quantified (n =400 structures per genotype). A t test was used to determine statistical significance, and error bars represent standard error of the mean.