A polypeptide having up to 14 amino acids, wherein the polypeptide is derived from the HD2 domain of human B-cell CLL/lymphoma 9 (BCL9), i) wherein the polypeptide comprises Xaa 1 LQXaa 2 LRXaa 3 IQRXaa 4 L (SEQ ID NO: 4), and wherein: a) the polypeptide is capable of undergoing a reaction to form one or more hydrocarbon crosslinkers, wherein Xaa 1 and Xaa 2 are each an α,α-disubstituted amino acid and a hydrocarbon crosslinker is present between Xaa 3 and Xaa 4 , or Xaa 3 and Xaa 4 are each an α,α-disubstituted amino acid and a hydrocarbon crosslinker is present between Xaa 1 and Xaa 2 ; or b) the polypeptide comprises one or more hydrocarbon crosslinkers, wherein: Xaa 1 , Xaa 2 , Xaa 3 , and Xaa 4 are each alanine, a first hydrocarbon crosslinker is present between Xaa 1 and Xaa 2 , and/or a second hydrocarbon crosslinker is present between Xaa 3 and Xaa 4 ; or ii) wherein the polypeptide comprises LQTLRXaa 1 IQRXaa 2 L (SEQ ID NO: 3), and wherein the polypeptide comprises a hydrocarbon crosslinker, wherein: Xaa 1 , Xaa 2 , are each alanine, and a hydrocarbon crosslinker is present between Xaa 1 and Xaa 2 . i) wherein the polypeptide comprises Xaa 1 LQXaa 2 LRXaa 3 IQRXaa 4 L (SEQ ID NO: 4), and wherein: a) the polypeptide is capable of undergoing a reaction to form one or more hydrocarbon crosslinkers, wherein Xaa 1 and Xaa 2 are each an α,α-disubstituted amino acid and a hydrocarbon crosslinker is present between Xaa 3 and Xaa 4 , or Xaa 3 and Xaa 4 are each an α,α-disubstituted amino acid and a hydrocarbon crosslinker is present between Xaa 1 and Xaa 2 ; or b) the polypeptide comprises one or more hydrocarbon crosslinkers, wherein: Xaa 1 , Xaa 2 , Xaa 3 , and Xaa 4 are each alanine, a first hydrocarbon crosslinker is present between Xaa 1 and Xaa 2 , and/or a second hydrocarbon crosslinker is present between Xaa 3 and Xaa 4 ; or a) the polypeptide is capable of undergoing a reaction to form one or more hydrocarbon crosslinkers, wherein Xaa 1 and Xaa 2 are each an α,α-disubstituted amino acid and a hydrocarbon crosslinker is present between Xaa 3 and Xaa 4 , or Xaa 3 and Xaa 4 are each an α,α-disubstituted amino acid and a hydrocarbon crosslinker is present between Xaa 1 and Xaa 2 ; or Xaa 1 and Xaa 2 are each an α,α-disubstituted amino acid and a hydrocarbon crosslinker is present between Xaa 3 and Xaa 4 , or Xaa 3 and Xaa 4 are each an α,α-disubstituted amino acid and a hydrocarbon crosslinker is present between Xaa 1 and Xaa 2 ; or b) the polypeptide comprises one or more hydrocarbon crosslinkers, wherein: Xaa 1 , Xaa 2 , Xaa 3 , and Xaa 4 are each alanine, a first hydrocarbon crosslinker is present between Xaa 1 and Xaa 2 , and/or a second hydrocarbon crosslinker is present between Xaa 3 and Xaa 4 ; or Xaa 1 , Xaa 2 , Xaa 3 , and Xaa 4 are each alanine, a first hydrocarbon crosslinker is present between Xaa 1 and Xaa 2 , and/or a second hydrocarbon crosslinker is present between Xaa 3 and Xaa 4 ; or ii) wherein the polypeptide comprises LQTLRXaa 1 IQRXaa 2 L (SEQ ID NO: 3), and wherein the polypeptide comprises a hydrocarbon crosslinker, wherein: Xaa 1 , Xaa 2 , are each alanine, and a hydrocarbon crosslinker is present between Xaa 1 and Xaa 2 . Xaa 1 , Xaa 2 , are each alanine, and a hydrocarbon crosslinker is present between Xaa 1 and Xaa 2 . <EOS>