TP53 and neoplasm: Similar to human PDAC and tissue from the primary iKras*p53* tumor (Fig. 2a,b), iKras*p53* PDAC cells in 3D culture upregulated phosphorylated ERK (pERK) (Fig. 2a) and phosphorylated S6 (pS6) (Fig. 2b), indicating activation of the MAPK and PI3K pathway, respectively.