PTPN11 and neoplasm: Another typical tumor island, demarcated by a rarefied tumor structure (indicated by arrows in Figure 8D) in which cells were positive for cleaved caspase 3, was composed of mostly viable (cleaved caspase 3–) tumor cells (Figure 8D), which expressed lower levels of SHP2 than did viable cells at the periphery of the island (Figure 8D).