Additionally, at the transcript and protein level these Mφ subpopulations express and secrete the enzymes arginase II (Arg2) and chitinase-3-like protein 1 (CHI3L1/YKL-40), and the anti-inflammatory cytokines IL-10 and TGF-β displaying leukaemia supporting and immunosuppressive properties (Mantovani and Allavena, 2015), as well as reducing cancer drug sensitivity (De Palma and Lewis, 2011, 2013; Figure 2). Here, CHI3L1 is linked to cancer.