MERTK and neoplasm: Meanwhile, apoptotic tumor cells display “eat-me” signals such as phosphatidylserine and calreticulin, which are recognized by receptors in macrophages responsible for efferocytosis, such as milk fat globule-epidermal growth factor-factor 8 (MFGE8), MerTK, Axl, and Tyro3 [18–21].