Effect of Osx on IL-1α protein production and IL-1α promoter activity. A. IL-1α protein levels in cell lysates were quantified by ELISA. The relative fold (pg/mg) was calculated as described in Materials and Methods. B. To determine the basal IL-1α promoter activity, K7M2 cells were transfected with the empty reporter (pGL3-basic), the IL-1α promoter reporter construct (pGL3-IL-1α), or the IL-1α promoter reporter vector in the reverse orientation [pGL3-IL-1α (reversed)]. Renilla luciferase construct was cotransfected for normalization. Luciferase activity was measured 24 h after transfection. Relative fold activity was calculated as the normalized pGL3-IL-1α or pGL3-IL-1α (reversed) activity divided by the normalized pGL3-basic value. C. K7M2 cells were cotransfected with IL-1α promoter reporter construct and either the expression plasmid for Osx (pTE-osx) or the control vector (pTE). Luciferase activity was measured 24 h after transfection. Relative fold activity was calculated as the normalized luciferase value divided by the normalized luciferase value in untreated K7M2 cells. D. IL-1α promoter reporter construct was transfected into K7M2, K7M2-neo, K7M2-osx-1, and K7M2-osx-2 cells. Luciferase activity was measured 24 h after transfection. Relative fold activity was calculated as described for C.