ALK and lung cancer: The leading cause of ALCL is a recurrent t(2;5)(p23;q35) chromosomal rearrangement that gives rise to a fusion protein, NPM::ALK, constituted of 117 N-terminal amino acids of NPM1 protein and the C-terminal part of ALK, including its catalytic domain [56], while the most frequent fusion protein in lung cancer is EML4::ALK found in 5–8% of NSCLC [57,58].