RB1 and small cell lung carcinoma: Furthermore, knockout of Pten allowed for the genesis of SCLC from alveolar cells in the context of Myc over-expression and Rb1/p53 knockout [53], which may partially explain the high prevalence of PI3K/AKT pathway mutations in T-SCLC patients [6,7,9,11,12,13,23,43,55].