PTEN and neoplasm: In the signaling that occurs in niches all pathways that regulate tumor progression and transformation and other processes are included, such as epidermal growth factor receptor (EGFR) gene amplification, phosphatase and tensin homolog (PTEN) mutation, PI3K/Akt, bone morphogenetic proteins (BMP), loss of heterozygosity (LOH) on critical chromosomal regions, etc., as well as the intrinsic signaling such as Wnt/β-catenin, Bmi1, c-Myc, Oct4, OLIG2, Sonic Hedgehog (SHH), and Notch.