In the previous reported PROTAC, Zhao et al. 30 used the N-terminal aspartic acid to promote formation of helical structures to enhance the stability and cell permeability, which helped the TD strategy-based PROTAC to form a complex with E3 ubiquitin ligase for effective degradation of ERα and inhibition of estrogen-positive breast cancer cell 31. Here, ESR1 is linked to breast cancer.