HSP90AA1 and fibrosarcoma: To identify novel proteins that act in invasiveness, we applied a functional proteomic screen using Fluorophore-Assisted Light Inactivation targeted with antibody libraries selected against proteins expressed on the surface of HT-1080 fibrosarcoma cells [2] This screen revealed three proteins newly implicated in invasion [3,4] and the most intriguing is extracellular Hsp90 (eHsp90).