PDGFRA and soft tissue sarcoma: These SNPs are located on genes that play secondary or less well-understood roles in dioxin response or toxin-metabolizing pathways, as well as SNPs on PDGFRA and 10 matrix metalloproteinase (MMP) genes, which are often over-expressed in GISTs and other soft tissue sarcomas and may be linked to tumor invasion and metastasis [23-25].