In order to characterize newly established human urinary bladder carcinoma cell lines (JTC-29, JTC-30, JTC-31, JTC-32, JTC-33 and JTC-34) by Kakuya et al. [In Vitro, 19, 591-599 (1983)], we investigated alkaline phosphatase in these cell lines. Relatively high alkaline phosphatase activity was found in JTC-29 and JTC-32 cells, but the enzyme activity in the other cell lines was very low. Prednisolone induced alkaline phosphatase activity even at 0.005 micrograms/ml (14 nM) and the effect was maximal at 0.05 micrograms/ml. NaCl also induced alkaline phosphatase activity at 50 mM. A further increase in the activity was observed at 0.1 M NaCl, but at 0.2 M all cells came off from plastic culture dishes without an increase in the enzyme activity during the incubation for 24 h at 37 degrees C. Both actinomycin D and cycloheximide abolished the increases in the enzyme activity with prednisolone or NaCl. The Lineweaver-Burk plot showed that the increases in the enzyme activity are due to the increases in Vmax, but not in Km. Alkaline phosphatase in JTC-32 cells and prednisolone-treated JTC-32 cells was heat stable and 100% of the initial enzyme activity remained after 30 min of incubation at 56 degrees C. However, the enzyme in JTC-29 cells was heat labile and its activity was reduced to less than 50% after 20 min of incubation at 56 degrees C. L-Phenylalanine was the strongest inhibitor for the enzyme reactions in JTC-32 cell homogenates among L-phenylalanine, L-leucine and L-homoarginine, whereas L-homoarginine was the strongest for the enzyme reactions in JTC-29 cell homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)