Table 1. Experimental differences between studies for cellular uptake of peptides.

Operational parameter	Examples
Technique	Spectrofluorometry		MALDI-TOF MS		Confocal laser scanning microscopy (CLSM)
	RP-HPLC		Flow cytometry (FACS)		Atomic Absorption Spectrometry
	Scintillometry		Splice correction assay		Quantitative image analysis of CLSM images
	Fluorescence microscopy		–		–
Positive control	No		Tat 48–60		Transportan 10
	Penetratin		Tat 47–57		Transportan
	MAP		R9		YGR6
	pVEC		D-R9		R8
Negative control	No		Dextran		Perforin
	No peptide used		YDEGE		STRRSAMAPR
	Green fluorescent peptide		YDEEGGG		APRTPGGRR
Units of quantitative data	µM or nM		pmol or nmol/mg cell protein		SI/mg cell protein
	ng/mg cell protein		a.u.		Fold change in GeoMean fluorescence
	Mean fluorescence intensity		RLU/mg		Mean fluorescence intensity/mg cell protein
	Fold/basal fluorescence		Relative fluorescence intensity		Relative cellular uptake (to control)
	% of total peptide		% of added peptide		% cellular uptake
	Cellular fluorescence		Fold change in FITC medium		–
Label	FITC		5,6-carboxyfluorescein		2-aminobenzoic acid
	Biotin		Deuterium		Rhodamine
	NBD		TAMRA		Alexa 488
	GaDOTA		Texas Red		125I
Cell line	AEC	BMC	HaCaT	HEK293	MC57	S. cerevisiae
	HBCEC	CHO (−K1)	Caco-2	HL60	A549	C. albicans
	bEnd	U2OS	Cos-7	MDCK	A431	E. coli
	MCF-7	Jurkat	MOLT-4	HeLa	Hela pLuc705	B. megaterium
	NIH-3T3	RAW264.7	BA/F3	K562	BT-20	N2a
	KB	RAW	U373 MG	Daudi	Sf9	MDA-MB-231
	HT-29	SKMel37	DAMI	A549	U251	KG1a
	TF-1	ESC	NC	Sca-1+Lin−	HEK293	L929
	Calu-3	MDA	HER	TM12	CCRF-CEM	–
Incubation concentration	10 nM	200 nM	0.1 µM	0.33 µM	0.4 µM	0.8 µM
	1 µM	1.8 µM	2 µM	2.5 µM	3 µM	3.1 µM
	3.5 µM	4 µM	4.5 µM	5 µM	6 µM	6.3 µM
	7.5 µM	10 µM	12.5 µM	15 µM	20 µM	25 µM
	30 µM	40 µM	50 µM	100 µM	110 µM	200 µM
	400 µM	800 µM	1.6 mM	–	–	–