Representative IF IHC-stained sections of MDBMSCC demonstrating the expression of pSTAT3 [(A), red] and EMA [(A), green] by cells within the tumor nests. There was a CSC subpopulation remonstrating nuclear co-expression of STAT3 [(B), red] and CD34 [(B), green], appearing as orange, on the endothelium of the microvessels within the stroma; and another subpopulation staining only positively for pSTAT3 within the stroma [(B), red]. Nuclear expression of NANOG [(C), red] was demonstrated on the endothelium of the microvessels which expressed CD34 [(C), green] within stroma. The NANOG+ cells [(C), red] that do not express CD34 were seen within the tumor nests and the stroma. SOX2 [(D), red] was also expressed by cells within tumor nests and the stroma, and the endothelium of the microvessels expressing CD34 [(D), green]. Nuclear expression of both SOX2 [(E), red] and SALL4 [(E), green], appearing as orange, was seen on the cells within the tumor nests and the stroma. Expression of both SOX2 [(F), red] and OCT4 [(F), green], appearing as orange, was seen on cells within the tumor nests and the stroma, and the endothelium of the microvessels within the stroma. pSTAT3 [(G), red] and membranous staining CD44 [(G), green] were co-expressed by cells within the tumor nests. Scale bars: 20 μm.