rase reporter assay The pGL3-OSMR-Pro2-get Clemizole hydrochloride luciferase construct designed to contain a CpG 21825001 island was kindly provided by Dr. Frederic Blanchard , and transfected into HEK293, HCT116 and SW480 cells at a density of 16105/well in a 24-well plate. For each well, 100 ng of the pGL3-OSMR-Pro2-Luciferase constructs was cotransfected with 10 ng of 16494499 internal control reporter pSV-Renilla using Fugene-6 in accordance with the manufacturer’s instructions. After 48 hrs, the luciferase assay was performed using a Dual luciferase assay kit and a single-sample luminometer. The luciferase activity was normalized by pSVRenilla activity, and the pGL3basic vector was used as a control. The pGL3-OSMR-Pro2-Luciferase construct and the pGL3basic vector were methylated in vitro using SssI methylase as recommended by the manufacturer’s instructions. After DNA isolation, equal amounts of the methylated or unmethylated luciferase constructs were transfected into cells. Each experiment was performed twice, each in triplicate. for detection of promoter methylation in CRC cell lines. UnM, unmethylated gene group; M, methylated gene group. Found at: doi:10.1371/journal.pone.0006555.s001 Knockdown of OSMR and cell growth assay A siRNA pool targeting OSMR and non-targeting control were purchased from Dharmacon. Fifty nM 
of each siRNA were transiently transfected to HCT116 using LipofectamineRNAiMax transfection reagent in OPTI-MEM. After 24 hrs, cells were incubated in complete growth medium. Initial cell seeding density was 56103/well in 24 well plates, and the antiproliferative activity of rhOSM was measured by the MTT assay. After 4 hr incubation in serum-deprived condition, cells were treated with rhOSM in 0.1% serum medium, and incubated for 2, 3, or 4 days as indicated. Stat3 inhibitor peptide purchased from Calbiochem was pre-treated for 1 hr and 30 min during serum starvation, and co-treated with rhOSM for 72 hrs. 5-Aza-dC was pre-treated for 48 hrs, and co-treated with rhOSM. Western blot analyses After pre-treatment with 5-Aza-dC or Stat3 inhibitor, rhOSM was treated in serum-free condition for 30 min, and whole cell lysates were extracted in RIPA buffer, separated on 412% gradient SDS-PAGE, and transferred to nitrocellulose. The blots were incubated with either anti-OSMR, anti-phospho-Erk, anti-phospho-Stat3, anti-Erk, anti-Stat3, or anti-b-actin antibody for 2 hrs at room temperature or 4 uC overnight. After antibody washing, the blots were incubated with their respective secondary antibody and detected with enhanced chemiluminescence reagents according to the supplier’s protocol. All antibodies were purchased from Cell Signaling Technology except anti-OSMR and anti-phospho-Erk and anti-bactin antibodies. Flow cytometry analysis Cell surface expression of OSMR on SW480 and DLD-1 cells was detected using an anti-OSMR-phycoethryin conjugated antibody. Mouse IgG-PE antibody was used as an isotype control. Cellassociated fluorescence was acquired by a FACScaliber fluorocytometer and analyzed using Cell-Quest software. Supporting Information OSMR Methylation in CRC Experiments were done in duplicate, and values indicate means6SD. , P,0.05. Found at: doi:10.1371/journal.pone.0006555.s005 Re-activation of OSMR by 5-Aza-dC treatment. Cell surface expression of OSMR was determined on SW480 and DLD-1 cells by flow cytometry. Values shown as insets correspond to the mean of fluorescent intensity ratios between cells with or without 5-Aza-dC treatment. Mouse IgG-PE antibody