Unexpectedly, we noticed that cells from some SCLC cell lines (N2N1G, 16T, 6PF) derived from the Rbf/f;Trp53f/f (DKO) and Rbf/f;Trp53 f/f;p130f/f (TKO) genetically engineered mouse models form long cellular protrusions into cell-free spaces (Figure 1A–B). The gene discussed is TP53; the disease is small cell lung carcinoma.