To assess the generalizability of KRAS4b diffusion behavior, we overexpressed and evaluated KRAS4bG12D mobility in various cell lines (Figure 1—figure supplement 2), such as pancreatic cancer lines harboring endogenous mutant KRAS4bG12D, a ductal epithelial cell line, and importantly, in MEF cell lines that are devoid of any endogenous RAS protein (Figure 1e), and in all cases, we observed similar diffusion behavior. This evidence concerns the gene KRAS and familial pancreatic carcinoma.