JKB MT cells (1.0 × 10⁴/mL) were plated in 1 mL of RPMI-1640 containing 0.8% methylcellulose, 10% FBS, and puromycin 2.0 μg/mL at a final concentration, and cultured in a humidified chamber at 40°, 37°, 34°, and 31°C. Macroscopically visible colony-forming units were counted after 5 days of culture. Standard deviation was calculated from three independent experiments. Student's t-test was used to determine the significant difference.