The expression of IL34 is heterogeneous among cancer types, and high IL34 levels can represent either a poor prognostic factor (i.e., liver and lung cancers)15,16 or a favorable prognostic factor (i.e., cervical or head and neck cancers; see the “prognostic summary” of IL34 at the Human Protein Atlas: www.proteinatlas.org). Here, IL34 is linked to cancer.