Table II.

Cell-penetrating peptide uptake mechanisms.

Study, year	Pathway	Main trait	Examples	Refs.
Vives et al, 1997	Direct penetration	Energy-independent	Tat peptide	(36)
Derossi et al, 1994	Direct penetration	Energy-independent	pAntp	(37)
Richard et al, 2003	Endocytosis	Energy-dependent	Polyarginine	(42)
Nan et al, 2011	Endocytosis	Energy-dependent	ARF (1–22)	(18)
Kawamoto et al, 2011	Via the formation of a transitory membrane structure	Formation of the inverted micelles	Arginine-rich peptide	(47)