MARK2 and breast carcinoma: MELK is a serine/threonine kinase belonging to the AMPK family of kinases known to regulate cellular metabolism.8 MELK was initially discovered as one of the three mRNAs uniquely expressed during early embryonic development.9,10 MELK is also one of the proliferation markers included in Food and Drug Administration-approved breast cancer prognostic panels, such as MammaPrint11,12 and PAM50,13 which are used to plan treatment for breast cancer patients and to predict cancer recurrence.