Phosphatidylinositol 3-kinases (PI3Ks) are lipid kinases that regulate diverse 
cellular processes including proliferation, adhesion, survival, and motility. 
Dysregulated PI3K pathway signaling occurs in one-third of human tumors. 
Aberrantly activated PI3K signaling also confers sensitivity and resistance to 
conventional therapies. PI3K has been recognized as an attractive molecular 
target for novel anti-cancer molecules. In the last few years, several classes 
of potent and selective small molecule PI3K inhibitors have been developed, and 
at least fifteen compounds have progressed into clinical trials as new 
anticancer drugs. Among these, idelalisib has advanced to phase III trials in 
patients with advanced indolent non-Hodgkin's lymphoma and mantle cell lymphoma. 
In this review, we summarized the major molecules of PI3K signaling pathway, and 
discussed the preclinical models and clinical trials of potent small-molecule 
PI3K inhibitors.