SLC31A1 and neoplasm: Androgens induce the expression of copper transporter 1 (CTR1, encoded by SLC31A1), thereby promoting cellular copper uptake and subsequent activation of AR-mediated transcription.1 Conversely, copper ions enhance AR nuclear translocation and DNA binding affinity, amplifying the expression of AR target genes, such as KLK3, which are involved in tumor proliferation.2 This bidirectional regulation forms a positive feedback loop: AR signaling upregulates copper import, while copper reinforces AR activity.