OCLN and lung cancer: Few data from earlier studies have indeed highlighted potential tumor promoting effects of elevated occludin expression such as promotion of glucose uptake [4], increased angiogenesis [42], modulation of growths signaling pathways such as MAPK/ERK [43,44], PI3K/Akt [43], and the Hippo pathway [45], or increased tumor aggressiveness after occludin knockdown in lung cancer cells [10].