YAP1 and neoplasm: Furthermore, single-molecule RNA fluorescence in situ hybridisation (smRNA FISH) showed a clear and highly significant mutual exclusion between Thbs1-expressing cells and cells showing YAP activation, as assessed by expression of the YAP targets Ctgf (Figure 5—figure supplement 1H), Cyr61 (Figure 5—figure supplement 1I), Sca1 (Figure 5C and D, Figure 5—figure supplement 1J), and indicating the presence of two distinct tumour cell populations: one Thbs1+/Sca1- (64.61% ± 29.14%) and one Thbs1-/Sca1+ (30.40% ± 27.72%) (Figure 5D).