It has been shown that imprecise cleavage of a primary or precursor RNA by Drosha or Dicer. respectively. may yield a group of microRNA (miRNA) variants designated as "isomiR". Variations in the relative abundance of isoforms for a given miRNA among different species and different cell types beg the question whether these isomiRs might regulate target genes differentially. https://www.roneverhart.com/Tokidoki-X-Hello-Kitty-and-Friends-1-Blind-Box/