MKI67 and breast ductal adenocarcinoma: In our study, we have found relevant pairwise correlations between ER, PR, and BCL2, however, factor analysis sheds the light into their true interdependencies: in the context of ductal breast carcinoma, we confirm that the HR and BCL2 expression is indeed highly inter-dependent and governed by the same latent factor of variation which is also characterized by inverse relation to Ki67 and HIF-1α.