CD68 and gastrointestinal stromal tumor: Li et al. identified a group of macrophage-like circulating tumor cells (ML-CTC) [121, 122]featured by the expression of both CD68 (macrophage cell marker) and KIT (GIST cell marker) in metastatic GIST, and proposed that these cells may be used to predict the relapse and metastasis of GIST in future studies [122].