THY1 and cancer: Double immunostaining of CD90 with CD24 [a cancer stem cell (CSC) marker of PDAC] revealed that CD90+ fibroblasts were clustered around CD24+ malignant ducts, indicating that CD90+ fibroblasts are involved in tumor-stromal interactions, promote the development of PDAC, and could be a promising marker for this cancer (Zhu et al. 2014).