FIG. 8.

Endogenous Siah-1 functions to regulate DCC proteolysis in cells. Western blot studies were carried out on lysates of COS-1 cells cotransfected with a DCC expression construct and a pcDNA3 construct containing no cDNA insert (lane 1), a Flag-tagged wild-type SIAH-1 cDNA (lane 2), a Flag-tagged RING-deleted SIAH-1 cDNA (lane 3), or SIAH-1 cDNA in the antisense orientation (lane 4). Increased expression of DCC relative to the control lane was seen with the RING-deleted form of Siah-1 as well in the antisense studies. The blot was stripped and reprobed with an antibody against Na⁺/K⁺ ATPase to confirm equal loading. The migration positions (in kilodaltons) of selected molecular mass markers is indicated to the left of the blots.