PTEN and non-small cell lung carcinoma: Various mechanisms can lead to the activation of the PI3K pathway in NSCLC, including genetic alterations such as activating mutations in the PIK3CA gene, loss of the tumor suppressor PTEN (phosphatase and tensin homolog), amplification of the EGFR (epidermal growth factor receptor) gene, or activation of upstream receptor tyrosine kinases [28].