ERBB2 and ependymoma: Our data also suggest that a more robust assessment of ependymomas for therapeutic purposes may await the application of a more sophisticated combination of histological and molecular approaches, but while markers of tumor cell proliferation, e.g. Ki-67 immunolabeling [9,26-28], and a few molecular abnormalities, e.g. copy number gain across chromosome 1q and ERBB2/4 receptor expression [29-32], have been proposed as prognostic indicators, insufficiently unambiguous data are available from large patient cohorts for the confident creation of such a scheme.