Table 1. MS Analysis for FFPE and Matched Fresh-Frozen Mouse Liver Tissue Extracted at Atmospheric (14.7 psi) or Elevated Hydrostatic Pressure (40,000 psi)^a.

tissue	pressure (psi)	protocolb	extraction conditions	%protein extractiond	unique peptide IDs	unique protein IDs
frozen, 30 days	14.7	1FI	on ice, 2.5 h	100%	10237	4727
frozen, 30 days	14.7	1FH	100 °C + 80 °Cb	100%	9964	4581
FFPE, 30 days	14.7	1A	100 °C + 80 °Cb	17%	5565	3449
FFPE, 30 days	40,000	1P	100 °C + 80 °Cb	77%	9621	5192
frozen, 1 year	14.7	2FH	95 °C, 3 min	100%	5872	3415
FFPE, 1 year	14.7	2A	95 °C, 1 h	18%	107	107
FFPE, 1 year	40,000	2P	95 °C, 1 h	79%	5180	3492

^aFFPE mouse liver was homogenized in extraction buffer and heated with or without elevated pressure. Fresh-frozen tissue was extracted either at atmospheric pressure using the indicated extraction condition or on ice for 2.5 h.

^bProtocol used for protein extraction (see Materials and Methods).

^cTissue was heated at 100 °C for 30 min; then the temperature was lowered to 80 °C for 2 h.

^dThe amount of protein extracted from fresh frozen tissue was set to 100%.