The answer lies in the molecular chaperone heat shock protein 90 (Hsp90), according to a recent report in Current Biology. ...Hsp90 inhibitors could induce a switch from yeast to filamentous ...
They do so indirectly, by preventing the chaperone HSP90 from associating with the protein it is assisting (known as its client). In fact, these drugs are specifically HSP90 inhibitors.