In basal-like breastcancer subtypes, overexpression of MEK5 in conjunction with ERK5 was associated with poorrelapse- and metastasis-free survival in patients who received chemotherapy compared topatients not treated with chemotherapy, which suggests that MEK5-ERK5 expression could serveas a predictive marker for patient benefit from systemic treatments in the ER-negativebreast cancer setting [24]. Here, MAP2K5 is linked to cancer.