A polypeptide having up to 14 amino acids, wherein the polypeptide is derived from the HD2 domain of human B-cell CLL/lymphoma 9, 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.