TLR9 and rheumatoid arthritis: Since the hypoxia-induced in vitro invasion and viability of TNBC cells expressing low levels of TLR9 was inhibited in vitro by chloroquine (9), a well-established malaria and rheumatoid arthritis drug that is known to interfere with endosomal signaling, the present study aimed to further characterize the anti-tumor efficacy of chloroquine against TNBC cells with differences in TLR9 expression.