A complex pattern of regulation of the cartilage matrix protein gene was revealed by transient expression experiments. A minimal promoter from positions -15 to +64 functioned in chondrocytes and fibroblasts. An enhancer located in the first intron exerted chondrocyte-specific stimulation on the minimal promoter activity. The same fragment, however, had a negative effect in fibroblasts. Between -334 and -15, a silencer was found which inhibited the gene expression driven from its homologous as well as heterologous promoters both in chondrocytes and fibroblasts. Additional positive and negative control regions were mapped further upstream of the promoter.