Figure 5.

Integrin-linked kinase (ILK) activation by Secreted protein acidic and rich in cysteine (SPARC) requires H₂O₂ release following transforming growth factor (TGF)-β stimulation in HFL-1 cells. (A) HFL-1 cells transfected with non-targeting control or SPARC siRNA were treated with or without TGF-β (2 ng/ml) for 16 h and then cell lysates were subjected to ILK assay. ILK activity was assayed by western blotting analysis of phospho-myelin base protein (MBP) level. (B) HFL-1 cells were transfected with non-targeting control or ILK siRNA for 24 h, starved of serum for 24 h, and then cell lysates were subjected to western blotting analysis for ILK expression. (C) HFL-1 cells transfected with non-targeting control or ILK siRNA were treated with or without TGF-β (2 ng/ml) for 16 h before H₂O₂ measurements. Data are expressed as means ± SE. Three replicate experiments showed similar results. **P <0.01 versus TGF-β-stimulated HFL-1 cells transfected with non-targeting control siRNA.