Runx2 is essential for the expression of secreted sclerostin and GM-CSF in MDA-MB-231 cells. (A and B) Runx2 regulates the activity of the SOST and CSF-2 promoter. MDA-MB-231 cells transfected with siRunx2 or a non-specific siRNA (siNS) were transfected with a plasmid containing either the SOST (A) or CSF-2 (B) promoter. Luciferase activities are presented as mean values ± SD All values are relative to the activity of the Renilla luciferase reporter. Insets show Western blots of Runx2 expression when transfected with siRNAs as indicated. (C and D) MDA-MB-231 cells transfected with the luciferase reporter constructs containing, either the SOST (C) or CSF-2 (D) wild-type promoter (WT), or the Runx site mutant (Mut). Data are presented as mean ± standard deviation (SD) (n = 3). All values are relative to the activity of the Renilla luciferase reporter. (E) ELISA showing sclerostin and GM-CSF in the media of MDA-MB-231 cells. Data are presented as mean ± standard deviation (SD) (n = 3). Statistical evaluation of significant differences was performed on all graphical data using the Student's t-test. Asterisk (*) indicates P < 0.05 when compared to controls.