Figure 1

Adhesion of monocytes to collagen stimulated a tyrosine kinase-dependent signaling response and a tyrosine kinase-independent decrease in full-length APP protein levels. A) THP-1 cells were either untreated or treated for 30 minutes with PP2 (5 μM) or DMSO vehicle. Cells were plated on tissue culture plastic alone or on type I collagen. B) THP-1 cells were either not transfected or transfected with individual APP siRNA duplexes. At 24 hours post-transfection, non-transfected cells were unstimulated (control) or stimulated by adhesion to collagen, and transfected cells were stimulated by adhesion to collagen. Cells were plated on tissue culture plastic alone or on type I collagen. Cells were lysed at 30 minutes in RIPA buffer, separated by 7% or 10% SDS-PAGE and Western blotted using anti-phosphotyrosine antibody, 4G10, anti-phospho-p38 antibody, anti-p38 antibody (loading control), anti-APP antibody, and anti-ERK2 antibody (loading control). Antibody binding was visualized by chemiluminescence.