This can work well for fixing of mammalian cells in preparation for immunolabeling and microscopy. Depending on the epitope, different fixatives may be required; membrane-bound epitopes may do better without permeabilization.
-Fixation Solution: 4% Formaldehyde in phosphate buffered saline (PBS) solution, pH 7.4 - 7.6 (verify)
-Permeabilization Solution: 0.1% Triton X-100 in PBS
1) For fixation, incubate cells in Formaldehyde Solution for 10-15 minutes at room temperature.
2) For permeabilization, remove Formaldehyde Solution, and incubate cells in Permeabilization Solution for 5 minutes at room temperature.
3) Rinse in PBS before proceeding.
For further information about fixing cells, see Immunocytochemistry.