Signature 4 is associated with smoking across several cancer types (Alexandrov et al., 2013; Nik-Zainal et al., 2015); interestingly, SMARCA4-d is seen in aggressive thoracic sarcomas (Sauter et al., 2017) and strongly enriched among patients with a history of smoking (Rekhtman et al., 2020). The gene discussed is SMARCA4; the disease is cancer.