- Microscopic FT-IR spectroscopy was used to investigate spectral differences between various primary cells obtained from different sources (mouse, rat, rabbit, and human) and malignant cells transformed by murine sarcoma virus (MuSV). The advantage of this method over conventional FT-IR spectroscopy is that it facilitates inspection of restricted regions of tissue. Our results showed significant and consistent differences between all the tested normal and malignant cells. An impressive decrease in the levels of vital cellular metabolites was seen in malignant cells compared to normal cells. The peak attributed to the PO2- symmetric stretching mode at 1082 cm-1 was shifted significantly to a higher frequency (1086-1087 cm-1) in all the tested malignant cells. The impressive and consistent differences between normal primary cells and malignant cells (obtained from various organs and species) in the shapes and position of various bands throughout the spectrum strongly support the possibility of developing FT-IR microscopy as a diagnostic method for the detection and study of cancer cells.