Soomro I, et al. - Given that Discoidin Domain Receptor 1 (DDR1) has been recently indicated to be up-regulated in various cancers and plays a role in tumor growth, progression, and invasion, researchers investigated the role of DDR1 in polycystic kidney disease pathogenesis. They also determined if it would offer an association between the extracellular matrix and regulation of growth of cyst lining epithelia. Using a new mass spectrometry approach, they found upregulated DDR1 as receptor tyrosine kinase in vivo in 3 mouse models of autosomal dominant polycystic kidney disease (ADPKD). However, no slowing of cyst growth or preservation of kidney function were seen with genetic deletion of DDR1 using CRISPR/Cas9 in both a rapid and slow mouse model of ADPKD. This implies that DDR1 has no role in PKD pathogenesis and therefore it is not a viable drug target.