. Author manuscript; available in PMC: 2023 Apr 1.

Published in final edited form as: J Cell Physiol. 2022 Jan 30;237(4):2220–2229. doi: 10.1002/jcp.30687

Table 3.

Effect of cell senescence on PAPP-A protein expression and proteolytic activity in NHLF

	PAPP-A^a	IGFBP-4^b	PAPP-A proteolytic activity^c
Non-senescent
Control	23 ± 4.3	17.5 ± 1.98	3.1 ± 0.61
TGF-β	49 ± 4.9^‡	11.1 ± 0.55^‡	3.6 ± 0.28

Senescent
Control	252 ± 42^*	64.1 ± 9.48^*	13.4 ± 9.0
TGF-β	276 ± 53^*	61.7 ± 7.40^*	14.1 ± 9.7

Non-senescent and senescence-induced NHLF were treated with SFM ± TGF-β (10 ng/ml) for 72 h. CM was collected and assayed for PAPP-A protein, total IGFBP-4 protein, and PAPP-A-mediated proteolysis of IGFBP-4. Results are mean ± SEM from three separate experiments.

PAPP-A protein; ng/10⁶ cells

Total IGFBP-4; ng/10⁵ cells

PAPP-A mediated IGFBP-4 proteolysis; Initial velocity,

by ANOVA

Significant effect of senescence, P < 0.05

^‡

Significant effect of TGF-β, P < 0.05