STAT3 and cancer: They used human thioredoxin devoid of cysteines as an optimal scaffold for the display of target-interacting peptides in a restricted conformation and generated recombinant proteins for the delivery of specific peptide aptamers to cells [152]; rS3-PA was shown to rapidly enter cancer cells, decrease STAT3 phosphorylation, and increase its proteasomal degradation, promoting cell growth arrest and apoptosis [153].