Several groups have successfully delivered CPP fused proteins "in vitro". TAT was able to deliver different proteins, such as horseradish peroxidase and RNase A across cell membrane into the cytoplasm in different cell lines "in vitro". The size range of proteins with effective delivery is from 30kDa to 120-150kDa. In one study, TAT-fused proteins are rapidly internalized by lipid raft−dependent macropinocytosis using a transducible TAT−Cre recombinase reporter assay on live cells. In another study, a TAT-fused protein was delivered into mitochondria of breast cancer cells and decreased the survival of breast cancer cells, which showed capability of TAT-fusion proteins to modulate mitochondrial function and cell survival. Moreover, cR10, a cyclic poly-arginine CPP, enabled the endocytose independent transduction of antigen binding proteins through the cellular membrane with immediate bioavailability. Thereby, the authors of the study were able to deliver fluorescent antigen binding proteins into cells facilitating live-cell immunostaining. However, very few in vivo studies have succeeded. In one study, in vivo delivery of TAT- or penetratin-crosslinked Fab fragments yielded varied organ distributions and an overall increase in organ retention, which showed tissue localization.