Early studies were the first to highlight the role of cytokines in radiation-induced toxicity, showing in preclinical and clinical lung models that levels of IL-1, transforming growth factor (TGF)-β, and tumour necrosis factor (TNF)-α increased immediately after radiation exposure, while persistently elevated TGF-β was associated with a higher risk of pulmonary fibrosis [32]. Here, TGFB1 is linked to pulmonary fibrosis.