- Hirai S, Yamanaka M, Kawachi H, Matsui T, Yano H. Activin A inhibits differentiation of 3T3-L1 preadipocyte. Mol Cell Endocrinol. 2005;232:21-6 pubmed..On the other hand, activin A treatment had no effect on the mitotic clonal expansion. These results indicate that activin A inhibits adipogenesis via affecting the transcriptional factor cascade upstream of PPARgamma expression. ..