The molecular mechanism of anticancer effects of fucoidan is summarized as the signaling pathways associated with the processes of apoptosis, cell cycle arrest, anti-angiogenesis, inhibiting metastasis (migration and invasion), etc. Our current finding proposed that fucoidan-induced apoptosis of lung cancer cell results from activation of the TLR4/ROS/ER stress axis and the mediation of downstream PERK-ATF4-CHOP signaling pathways. Here, ATF4 is linked to lung cancer.