This invention provides cellular regulators of antitumor agent apratoxin
A. The invention also provides methods for identifying novel antitumor
compounds using these cellular regulators of apratoxin A. The methods
comprise first screening test agents for modulators of a cellular
regulator of apratoxin A and then further screening the identified
modulating agents for antitumor activities. The invention further
provides methods and pharmaceutical compositions for treating tumors in a
subject.