TGFB1 and posterior cortical atrophy: Thus, it triggers our interest to determine whether TGF-β signaling is upregulated in PCa CSCs by detecting the mRNA expression of its downstream signaling components like SMAD7, PAI-1 and P21. The results from real-time PCR demonstrated that TGF-β signaling-related genes are significantly increased in first-passage spheres as compared with cells from which spheres derived (Figure 1A and Supplementary Figure 1A).