Considering that many SMIs such as OTX-015 often lead to the accumulation of BRD4 and the incomplete inhibition of cancer cell growth [65], Winter et al. synthesized the first BET-targeting PROTAC dBET1 (Fig. 6) that was composed of the SMI JQ-1 and the CRBN ligand thalidomide through an eight-atom linker N-butyl-2-hydroxyacetamide [58]. Here, BRD4 is linked to cancer.