Occurrence of a low-molecular-weight calcium-binding protein in neoplastic liver.

A calcium-binding protein was detected in the cytosol of Morris hepatomas 7288, 5123tc (h), 5123tc, and 7795. This protein could not be detected in adult Buffalo liver, 24-hr regenerating liver, or 18- to 20-day-old fetal liver. The amount of this protein present was not clearly related to the growth rate of the tumors studied, although there was more in a faster growing tumor (5123tc) than in the slowest (7795). The protein from the four tumors was apparently identical. The calcium-binding protein was heat stable and was not the calcium-dependent regulator of cyclic nucleotide phosphodiesterase. It had an apparent molecular weight of less than 12,500.