SMAD3 and lung cancer: In this study, by dissecting the MMT signaling in lung cancer with our macrophage‐lineage specificscRNA‐seq dataset[18] and unbiased bioinformatics, we unexpectedly discovered a hematopoietic transcription factor Runx1[19] is highly expressed in the MMT cells (MMTs) and serves as a key downstream regulator in the macrophage‐specific TGF‐β1/Smad3 signaling for MMT initiation.