CCN2 and neoplasm: Tumor cell secreted factors (for example, TGF-β, PDGF, EGF, CTGF, and FGF [Varga and Jimenez, 1986; Gardner et al., 2004; Postlethwaite et al., 1987; Montesano and Orci, 1988; Kuzet and Gaggioli, 2016; Löhr et al., 2001; Takehara, 2000]), and tumor cell-derived exosomes, have been implicated in fibroblast activation (Ringuette Goulet et al., 2018).