A 56-year-old man presents to the physician for a 1-week history of dark-colored urine. He reports no recent illnesses or infections. One year ago he underwent a cadaveric liver transplant for fulminant alcoholic hepatitis. An agent with which of the following mechanisms of action is most likely responsible for this patient’s acute presentation?
Alkylation of guanine N7
Decreases intracellular calcineurin
Inhibition of CD20
Inhibition of mTOR
Inhibition of dihydrofolate reductase
