RHOA and nonpapillary renal cell carcinoma: In the continuous presence of shRNA to Activin B a similar autocrine induction of Activin B is unlikely to cause the stable reversion of the knockdown ccRCC cells, yet it is possible that cells produce other factors such as TGFβ or Activin A that substitute for Activin B. It is currently unclear how Activin B and RhoA signaling are connected on a molecular level.