In both in vitro and in vivo studies, Whitt et al. [56] targeted the SV2 receptors on pancreatic and medullary thyroid cancer cells by a conjugate of the recombinant heavy chain receptor binding domain of BoNT-A (rHCR) and an anti-mitotic agent monomethyl auristatin E (MMAE). This evidence concerns the gene SLC3A2 and medullary thyroid gland carcinoma.