2.3 Cell viability assay
Cell viability was measured with MTS Assay Kit (Promega, Madison, WI, USA) according to the manufacturer’s instructions. Pancreatic cancer cell lines were seeded in 96-well plates at 2,000-5,000 cells per well (depending on the cell lines used). After incubation for 24 h, the cells were treated with TA at concentrations ranging from 0 to 10 μM for 48 h or 72 h. Then, 20 μL of MTS solution was added directly into each well, and the 96-well plates were incubated at 37 °C in a humidified incubator with 5% CO2 for 1-2 h. The absorbance of each well at 490 nm was recorded using a 96-well plate reader (Bio-Rad, Hercules, CA, USA).