Fig. 1. TRPV4 mRNA is expressed in volume-regulating cells. Total RNA was isolated from HaCaT keratinocytes, distal renal tubule cells (DTC), proximal renal tubule cells (PTC) and CHO cells. A region in the TRPV4 ORF and the glyceraldehyde-3-phosphate-dehydrogenase (GAPDH) ORF were amplified by RT-PCR with gene-specific primers and separated on a 1.5% agarose gel. No PCR product could be detected in CHO cells.