It was reported that 4-(methylnitrosamine)-1-(3-pyridine)-1-butanone (NNK) derived from nicotine could promote the formation of cell spheres and increase the expression of cell surface markers CD44, OCT4, C-MYC and NANOG in HCT8 and DLD-1 cells (21), while exposure to NNK could significantly enhance the proliferation and growth ability of CRC cells. This evidence concerns the gene CD44 and colorectal carcinoma.