TGFB1 and cancer: Considering that TERT-siSFRP1 cells exhibit cancer initiating-cell-like characteristics and display a CD44high/CD24low cell surface marker expression pattern [16,30], our current results are fully consistent with previously published research by Shipitsin et. al showing that CD44high/CD24low cells are more responsive to TGF-β and can be specifically targeted by TGF-βR inhibition [31].