FAP and breast carcinoma: Additionally, Wong et al. discovered that in OSCC cells, FAP mediates the ERK/RAS pathway to promote tumor progression and invasion [51]; however, Jia et al. found that the addition of PI3K or ERK inhibitors failed to restore the inhibitory effect of FAP in breast cancer cell lines, suggesting that the PI3K or ERK signaling pathway may not be a downstream target of FAP [52].