We used the following PCC lines: AsPC-1, CFPAC-1(American Type Culture Collection, Manassas, VA, USA), Panc-1 (Riken BioResource Center, Ibaraki, Japan), SUIT-2 (Japan Health Science Research Resources Bank, Osaka, Japan), and BxPC-3 (National Kyushu Cancer Center, Fukuoka, Japan). All PCCs were maintained in DMEM (Sigma Chemical Co., St. Louis, MO, USA) supplemented with 10% FBS at 37 °C with humidified 90% air and 10% CO
2. Human pancreatic ductal epithelial (HPDE) cells were obtained from Dr. M.-S. Tsao (University of Toronto, Canada) and maintained in HuMedia-KG2 medium (KK-2150S Kurabo, Osaka, Japan). We established human PSCs from fresh pancreatic cancer surgical specimens using the outgrowth method [
19‐
21], as described in our previous reports. The isolated cells were confirmed to be PSCs by their spindle-shaped morphology, and immunofluorescence staining for αSMA, vimentin, CD90, glial fibrillary acidic protein, and nestin, but not CK19 [
22,
23]. They were used within eight passages for each assay. Immortalization of PSCs was conducted as described previous [
23]. All PSCs were maintained in DMEM (Sigma-Aldrich Co., Tokyo, Japan) supplemented with 10% fetal bovine serum, streptomycin (100 mg/ml), and penicillin (100 mg/ml) at 37 °C in a humidified atmosphere containing 10% CO
2. HPaSteC cells (#3830; ScienCell Research Laboratories, Carlsbad, CA, USA) were maintained according to the manufacturer’s instructions using Stellate Cell Medium (#5301; ScienCell). PCCs from primary tumors in KPC mice were established using an outgrowth method [
19], and isolated cancer cell lines were maintained as described [
24]. ERK1/2 inhibitor used in vitro (S7101, Selleck Chemicals, Houston, TX, USA) and in vivo (HY-50846, MCE, NJ, USA) were reconstituted following the manufacturer’s recommendations and used at the indicated doses. Chloroquine phosphate was purchased from Sigma-Aldrich (#PHR1258), dissolved in phosphate-buffered saline to 10 mM, and stored at
−20C until used.