Restoration of TGFβ signaling suppresses enhanced cell survival signaling in vitro . The native CBS cell line (low expression of TGFβRII receptor) and CBS-RII (transfected with TGFβRII) were utilized to demonstrate that re-introduction of TGFβ signaling results in suppression of cell survival signaling. CBS and CBS-RII cells were grown to 80% confluence, and subjected to GFDS for 48 h followed by subcellular fractionation to separate cytosolic from mitochondrial fractions. Western blot analysis was used to probe XIAP and survivin. Tubulin and porin proteins were used as compartmentalization controls for cytosol and mitochondria, respectively.