P815 (mast cell; mastocytoma)Mouse P815 cells were cultured in DMEM and harvested at the log phase of growth. The P815 cells were fixed in 4% paraformaldehyde and arrayed on a 12-well (5 mm) adhesive coated slide, with each wellis surface specifically treated to enhance cellular attachment and to minimize background staining. Each well was loaded with approximately 7.5 x 103 P815 cells. A follow-up heat dehydration process was done to ensure the attachment of P815 cells and the stability of cellular proteins.