SMAD7 and colorectal carcinoma: Block of CRC cells in the S phase in response to Smad7 antisense treatment is followed by enhanced cell death.6 Therefore, we next performed Annexin V (AV)/propidium iodide (PI) staining of cells treated as above to determine whether silencing of PKR and consequent inactivation of eIF2α abrogated Smad7 antisense-driven cell death.