a, KPsh embryonic-stem-cell-based genetically engineered mouse model of PDAC. Embryonic stem cells express PDX1–Cre (transgenic expression of Cre in pancreatic progenitors), LSL–KRAS(G12D) (knock-in, conditional heterozygous expression of mutant KRAS), RIK (knock in, conditional heterozygous expression of rtTA and fluorescent mKate2 from the Rosa26 locus) and Col1a1-TRE-GFP-shp53-shRenilla (a COL1A1 homing cassette targeted with doxycycline-inducible tandem shRNA expressing p53 and Renilla linked to GFP). KPsh mice were generated by blastocyst injection and mothers were enrolled on doxycycline chow at day 5. Cell lines were derived and maintained in doxycycline-containing medium, from tumours that arose in doxycycline-fed mice. All KPsh cells constitutively express mKate2 and rtTA. b, Population doublings of KPsh no. 1, KPsh no. 2 and KPsh no. 3 lines grown on or off doxycycline. c–f, Characterization of levels of p53 (c), BrdU incorporation (d), annexin V staining (e) and senescence-associated β-galactosidase staining (f) in three independent KPsh lines grown on or off doxycycline. D, day. g, Representative gross pathology and epifluorescence images of pancreatic tumours that resulted from orthotopic transplant of KPsh no. 2 cells into doxycycline-fed mice maintained on doxycycline chow (top, n = 3 mice) or withdrawn from doxycycline chow for ten days (bottom, n = 3 mice). KPsh cells uniformly express mKate2 (Kate), wherease GFP expression indicates cells that actively express shRNA targeting p53. h, Representative p21 immunostaining in matched normal host pancreas, or in orthotopic KPsh no. 2 tumours maintained on doxycycline (n = 3) or ten days after doxycycline withdrawal (n = 3). mKate2 indicates injected KPsh no. 2 cells. i, Representative Ki67 immunostaining in orthotopic KPsh no. 2 tumours maintained on doxycycline (n = 3 mice) or ten days after doxycycline withdrawal (n = 3 mice). mKate2 indicates injected KPsh no. 2 cells. j, Small animal ultrasound measurement of tumour volume. KPsh no. 2 cells were injected into doxycycline-fed mice and mice were maintained on doxycycline diet for two weeks. After two weeks (D0), tumour size was measured and mice were randomized into off (n = 6 mice) and on doxycycline chow groups (n = 3 mice). Subsequent tumour size was measured at the indicated time points. n = 3 mice on doxycycline were collected for analysis upon being euthanized; n = 3 mice were analysed after 5 and 10 days of doxycycline withdrawal; n = 3 mice were analysed after 5, 10, and 18 days of doxycycline withdrawal. k, Survival of mice shown in i after randomization into groups maintained on doxycycline chow (n = 3 mice) or after doxycycline withdrawal (n = 6 mice). Experiments in b–f were repeated twice with similar results. Data are presented as representative, independently treated wells (c, f) or mean ± s.d. of n = 3 independently treated wells with individual data points shown (b, d, e). For gel source data of c, see Supplementary Fig. 1. Scale bar, 1 cm (g), 50 μm (h, i). Source Data