SPP1 and colorectal carcinoma: Based on studies of the correlated mechanisms between expression of OPN and metastasis in combination with the pertinent literatures, we concluded that a potential mechanism of OPN promoting CRC liver metastasis is as follows: CRC cells express OPN, the homogeneity adherence ability are decreased, the function of GJIC is inhibited, the capability of invasion and movement is increased, which makes it easy for the CRC cells to depart from primary lesion, get into circulation and initiate the procedure of metastasis.