TREM2 and neoplasm: In animal studies, TREM2 expression was shown to be induced by M-CSF, IL-4, and IL-13 stimulation of mouse macrophages in vitro and to be present in tumor-associated suppressive M2-like macrophages (Cella et al. 2003; Molgora et al. 2020; Turnbull et al. 2006).