FIG. 4.

MNV-1 infection triggers the mitochondrial pathway of apoptosis. Cytosolic and mitochondrion-enriched protein fractions were isolated from mock- and MNV-1-infected RAW264.7 cells collected at 16 h p.i. and at 8 and 16 h p.i., respectively. (A) The collected cytosolic proteins were probed with antibodies specific to mitochondrial marker protein COX IV to verify the absence of contamination with mitochondrial proteins. (B) The loading amounts of mitochondrial and cytosolic protein samples were normalized using total protein content and verified by probing with ß-actin-specific antibodies. (C) Cytochrome c release from the mitochondria was examined using normalized amounts of cytosolic (lanes 1, 3, and 5) and mitochondrial (lanes 2, 4, and 6) protein samples and cytochrome c-specific antibodies. Quantification of the cytochrome c release was performed using densitometry with the help of ImageQuant software (Molecular Dynamics).