MUC5AC and neoplasm: These iPSCs were originally generated via Sendai virus‐based transduction of reprogramming factors in human nasal epithelial cells.[30, 31] We previously demonstrated that chronic exposure to As3+ for 3 months induces tumor formation in these iPSCs, with tumors exhibiting histological features of both lung squamous cell carcinoma and mucin‐producing adenocarcinoma.