Although the precise mechanism of CTX targeting has yet to be fully elucidated, a number of studies have suggested the presence of many targeting receptors for CTX on the surfaces of different cancer cells, including chloride channels [45,46,47], MMP-2 [48,49,50], annexin A2 [51,52], estrogen receptor alpha (ERα) [53] and neuropilin-1 receptor (NRP-1) [54,55]. Here, ESR1 is linked to cancer.