FOLH1 and prostate cancer: After radiolabelling the RNA aptamers which are specific for PSMA, the [64Cu]Cu-NOTA and [64Cu]Cu-PCTA RNA aptamers demonstrated significantly greater binding affinity to the PSMA-positive prostate cancer cells, 22Rv1[1.7], than the PSMA-negative prostate cancer cells, PC-3, similarly to the unconjugated radiolabelled RNA aptamer [122].