MMP12 and Burkitt lymphoma: Like BL cells, λ-MYC lymphoma cells, especially when apoptotic, were able to activate MMP2 and MMP12 expression in macrophages in vitro (Figures 5F–5H) and promote the expression of a variety of SS-TAM markers in bone marrow-derived macrophages (BMDMs) (Figures S5A and 5I).