Table 3.

Differences between the DKK family members

Property	DKK1	DKK2	DKK3	DKK4	Ref.
Variants	Unknown	Unknown	2	Unknown	[130]
Location of Cys-1	85-138 amino acids	78-127 amino acids	147-195 amino acids	41-90 amino acids	[110]
Location of Cys-2	189-263 amino acids	183-256 amino acids	208-284 amino acids	145-218 amino acids	[110]
Length of linker region (number of amino acids)	50	56	12	54	[110]
Receptor	LRP5/LRP6	LRP5/LRP6	Not identified	LRP5/LRP6	[113]
Activity in Wnt/β-catenin signalling in HCC	Antagonist	Not reported	Not reported	Not reported	[126]
Expression in HCC tissues	Overexpressed	Reduced	Reduced	Not reported	[126,143]
Phenotype of knockout mice	Embryonic lethality	Viable, fertile, blindness, osteopaenia	Viable, fertile, hyperactive, increased IgM, natural killer cells and haematocrit levels	Not reported	[116,162-164]

Cys-1: Amino-terminal cysteine-rich domain; Cys-2: Carboxyl-terminal cysteine-rich domain; HCC: Hepatocellular carcinoma; LRP: Lipoprotein receptor-related protein; DKK: Dickkopf.