AKT1 and angiosarcoma: Furthermore, sustained endothelial Akt activation is known to cause increased blood vessel size and generalized edema from chronic vascular permeability.49 Consistent with the reports that high levels of phosphorylated Akt is observed in angiosarcoma,46, 50, 51 angiosarcoma derived from the TCL1b-deregulated mice showed to be positive with phospho-Akt using immunohistochemistry.