PDGFRB and breast cancer: By regulating mesenchymal cells such as fibroblasts, pericytes and smooth muscle cells, PDGFs and their receptors can promote tumor metastasis [117,118].• Loss of miRNA let-7d and gain of HIF1 activity promote breast cancer brain metastasis via PDGF; inhibition of PDGFR suppresses brain metastasis [119].• In pericytes and stromal fibroblasts, the PDGF-BB-PDGFRβ-IL-33-ST2 axis recruits TAMs and induces metastasis [120].• PDGF-C secreted by CAFs promotes GIST growth and metastasis [121].• PDGF-BB induces pericyte-fibroblast transition (PFT), contributing to tumor invasion and metastasis [122].