AASDHPPT and cancer: In particular, cancer cell membranes typically have a greater negative surface charge than that of normal cells due to containing a large fraction of anionic, phosphatidylserine (PS) lipids on the outer leaflet (by contrast, PS lipids are normally restricted to the inner leaflet of non-cancer cells) [15], which enables positively charged ACPs to preferentially bind to them [2,4,6,16].