Effects of LN on Gem-induced cytotoxity in AsPC-1 cells. AsPC-1 cells were treated as described in results. A, The cell viability of AsPC-1 cells of different groups was determined by MTT assays. Results were expressed as the percentages of viable cells compared with cells on plastic without Gem treatment (left). The cell viability was statistically compared at 72 h after Gem treatment (right). B, The long-term clonogenic potential of pancreatic cancer cells was evaluated by clonogenic assay. AsPC-1 cells on plastic or LN were treated with or without Gem (0.1 μM) for 24 h in SITA medium. Cells were then trypsinized and seeded in equal numbers into 24-well plates. After14 to 18 days, the mean number of the colonies was counted, and the inhibition rate was defined by comparison of the colony number of each group with that of cells on plastic without Gem treatment.