Table 2.

Mechanisms of Activin Social Network Function in Breast

Activin Network Member	Model	Outcome	Investigator
Activin A	Activin A treatment of human mammary epithelial organoids	Inhibits HGF-induced tubule formation	Liu et al. (24), 1996
Activin A	Activin A treatment of luminal breast cancer cell lines	Induces G1 cell cycle arrest dependent on activin-induced SMAD and p38/MAPK signaling	Burdette et al. (63), 2005
Activin A	Activin A treatment of luminal breast cancer cell lines	Inhibits estrogen-induced transcription activity and estrogen inhibits activin B expression and SMAD signaling	Burdette and Woodruff (65), 2007
Activin A	Genotoxic stress of mammary epithelia and stromal fibroblasts	Increased activin A leading to COX-2 and cytokine induction, promotes protumorigenic cancer-associated fibroblasts and desmoplasia	Fordyce et al. (66), 2012
Activin A	Activin A treatment of mammary epithelial cells	Represses CD36 expression in adjacent fibroblasts contributing to dense breasts and increased breast cancer risk	DeFilippis et al. (67), 2012; DeFilippis et al. (68), 2014
Activin/Nodal	Activin/nodal inhibition of Luminal and basal breast cancer cell lines	Interconversion of differentiated breast cancer cells into cancer stem cells	Meyer et al. (69), 2009
Activin A	Activin A overexpression in luminal or knockdown in basal breast cancer cell lines	Activin A promotes and is necessary to maintain the CD44+/CD24− cancer stem cell population	Bashir et al. (22), 2015
Activin A	Overexpression or treatment with activin A of breast cancer cell lines	Activin A overexpression or treatment promotes migration, invasion and select EMT characteristics in breast cancer cell lines	Bashir et al. (22), 2015; Seachrist et al. (28), 2017; Neel and Lebrun (70), 2013

Abbreviation: HGF, hepatocyte growth factor.