Functional role of Abi1 phosphorylation in MMP-9 secretion and CRC cell invasion. A , western immunoblotting of CHD1 cell lysate after control (DMSO) treatment or application of STI571 as indicated confirms inhibition of Abi1 Y435-phosphorylation through STI571, while levels of total Abi1, phospho-Erk1/2 and total Erk1/2 slightly increase upon STI treatment. Levels of cleaved caspase-3 are barely detectable. B , MMP-9 ELISA from cell culture supernatant after control (DMSO) treatment or application of STI571 shows a non-significant decrease in MMP-9 secretion after treatment with 5-50 μM STI571. C , increasing concentrations of STI571 inhibit CHD1 CRC cell invasion through reconstituted basement membrane in a dose-dependent manner. Representative microphotographs (right) show DAPI-counterstained cells that invaded through the sealed pores and were harvested from the lower chamber. DMSO, dimethyl sulfoxide; MMP-9, matrix metalloproteinase 9; n.s., not significant. *p