FSD1 and hyperinsulinemic hypoglycemia, familial, 4: To determine whether the decrease in AGO1 protein content also affected its functionality under Cu deficiency, the expression of several Cu-miRNA targets (ARPN, miR160 target; CCS, CSD1, and CSD2, miR398 targets; GSTU25, miR396 target; LAC3, miR397 target) was analyzed by RT–qPCR in 10-day-old Col-0, fsd1-2, and ago1-25 seedlings (Fig. 5A).