Drug-induced keratin 9 interaction with Hsp70 in bladder cancer cells.

A pull-down experiment (co-immunoprecipitation) was performed on a T24 human bladder cancer cell lysate treated with the Hsp inhibitor VER155008 using an Hsp70 antibody attached to Dynabeads. Keratin 9, a cytoskeleton intermediate filament protein, was identified by LC MS/MS analysis. This novel finding was confirmed by Western blotting, RT-PCR, and immunocytochemistry. Other members of the keratin family of proteins have been shown to be involved in cancer progression, most recently identified to be associated with cell invasion and metastasis. The specific role of keratin 9 expression in these cells is yet to be determined.