Further mechanism dissection studies suggested that the tumor suppressor function of TAP was via down regulation of phosphoinositide 3 kinase ( PI3K ) / Akt signaling , but not by modulating cell cycle arrest or androgen receptor signaling . ^^^ Immunoprecipitation results indicated that TAP inhibited the interaction of PI3K subunits , p 110 with p 85 , and subsequently reduced Akt activity . ^^^