Cell experiment:

Cells are plated in complete DMEM in 96-well tissue culture plates at 4×103/well. After 24 h, cells are washed with PBS and treated with peptides (50 μM) in SF-DMEM. Cell viability is determined by staining unfixed cells with calcein AM/ethidium homodimer, followed by microscopic analysis of cell staining and cellular morphology on a Nikon Diaphot 300 inverted microscope equipped with a fluorescence module.

Bak BH3 is derived from the BH3 domain of Bak, can antagonize the function of Bcl-xL in cells.

Bak BH3 peptide antagonize the protective effects of microinjected Bcl-xL in α-Fas-treated HeLa cells, whereas a mutant Bak BH3 peptide that no longer binds Bcl-xL is inactive[1].

[1]. Holinger EP, et al. Bak BH3 peptides antagonize Bcl-xL function and induce apoptosis through cytochrome c-independent activation of caspases. J Biol Chem. 1999 May 7;274(19):13298-304.