Broadening the scope to fibrocytes, we examined the functional contribution of these cells to lung cancer progression and metastasis by first more deeply characterizing fibrocytes via single cell transcriptomics, followed by selective in vivo−depletion techniques as well as co-application of fibrocytes with lung cancer cells in both xenograft and KRas-driven lung tumorigenesis models. Here, KRAS is linked to lung carcinoma.