MMP7 and neoplasm: Collectively, our current results suggest strongly that the two sorted subsets of RCC52 have their own CSCs and the ability to exhibit different levels of specific patterns of MMP mRNAs expression and their inhibitors (i.e., higher levels of MMP -2, -9 and TIMP-2 by the CD44bright/CD24dim sorted cells vs. higher levels of MMP-7, -8, and TIMP-1 by the CD44bright/CD24bright sorted cells), thereby ensuing divergent functional roles in tumor progression.