Table 1.

Abilities of the pappalysins (PAPP-A and PAPP-A2) to proteolytically cleave the six IGFBPs

Substrate	PAPP-A	PAPP-A2	Effect of IGF on cleavage	Reference
IGFBP-1	no	no	–	–
IGFBP-2	YES	no	Enhanced	1
IGFBP-3	no	YES	Enhanced	2
IGFBP-4	YES	no	Enhances (IGF is required)	3, 4
IGFBP-5	YES	YES	Decreased (PA)/Enhanced (PA2)	2, 4
IGFBP-6	no	no	–	–

References: 1 (Monget et al. 2003), 2 (Overgaard et al. 2001), 3 (Lawrence et al. 1999), 4 (Laursen et al. 2001)