PIK3CD and acute myeloid leukemia: Causes of PI3K/Akt/mTOR signaling up-regulation in AML may be the result of several factors, including activating mutations of Fms-like tyrosine kinase 3 (FLT3) receptor [71] and c-Kit tyrosine kinase receptor [78], N- or K-Ras mutations [79], PI3K p110β and/or δ overexpression [80-82], low levels of PP2A [70], autocrine/paracrine secretion of growth factors such as IGF-1 [82-84] and VEGF [85, 86].