PLG and infection: Although the β subunit has not yet been used as an anti-infection drug target, some small molecules and monoclonal antibodies targeting the β subunit have entered phase I or II clinical trials in antitumor studies, such as angiostatin, Hai178, and Aurovertin B, all of which have shown selective inhibition of tumor cells with low toxicity to normal cells (Moser et al., 2001; Huang et al., 2008; Chen et al., 2016).