Spheroid development. [A] Different PDAC cell lines grown in 3D culture for 4 days. According to the grading system by Sipos et al., Panc-1, BXPC3 and ASPC-1 are poorly differentiated and carry both mutant KRAS and p53 (Panc-1) or either p53 (BXPC3) or KRAS (ASPC-1), whereas Capan-1 is a well differentiated PDAC cell line. A previously established pancreatic stellate cell line (PSC) is also included as a non-transformed control cell line. [B] Development of a single representative Panc-1 spheroid, photographed from day 2 to day 8 by counting with the Boyden chamber the cell number of trypsinized spheroids and taking pictures of spheroids at fixed time points. [C] Cell counts from 2D and 3D cultures at different time points. Bars correspond to 500 μm.