PDGFC and chondrosarcoma: This study analyzed PDGF-C expression in human tissue specimens consisting of normal cartilage (n = 7), grade 1 chondrosarcoma (n = 11), grade 2 chondrosarcoma (n = 4), grade 3 chondrosarcoma (n = 6), and grade 4 chondrosarcoma (n = 3) (Figure 1a,b).