PTEN and lung cancer: Effects of Lactucin on metabolic markers of lung cancer cells were observed through WB, Figure 4A. Protein lysate from 24 h 80 μM Lactucin-treated A549 cells showed a different level of expression of metabolic markers, Figure 4B. Lactucin dose-dependently increased the expression of PTEN, a tumor suppressor protein that negatively regulates the activation of Akt to p-Akt, Figure 4 [26].