Targeting of let-7d-5p and -3p at the IGF1R and KRAS mRNAs, respectively. The IGF1R and KRAS mRNAs are depicted showing the coding sequence (CDS), the 5’- and 3’-UTR (horizontal lines) and the polyA sequence (An). The three let-7d-5p target sites in the 3’-UTR of IGF1R transcript and the single let-7d-3p site in the KRAS mRNA are shown by solid vertical bars. The seed sequences of the miRNA alignment with the target transcripts are boxed. mfe, minimal free energy.