NKX2-1 and neoplasm: The variable levels of Nkx2-1 and Sftpc in clusters 4–8 (Figure 4F) suggests that some of these cells represent higher grade tumor cells that stochastically lose NKX2-1 activity and expression, as has been documented in KRASG12D-driven GEMMs (Snyder et al., 2013; Winslow et al., 2011).