Methods and assays examining expression of one or more biomarkers in a mammalian tissue or cell sample are provided. According to the disclosed methods and assays, detection of the expression of one or more such biomarkers is predictive or indicative that the tissue or cell sample will be sensitive to apoptosis-inducing agents such as Apo2L/TRAIL and anti-DR5 agonist antibodies. Certain biomarkers which may be examined include fucosyltransferases, in particular fucosyltransferase 3 (FUT3) and/or fucosyltransferase 6 (FUT6), as well as sialyl Lewis A and/or X antigens. Kits and articles of manufacture are also provided.