Our results show that the expression of P-gp at protein level in NCI-ADR-RES (Figure 3A) and KB-V-1 (Figure 3B) cancer cells was not significantly altered by branebrutinib over a period of 72 h, suggesting that branebrutinib reverses P-gp-mediated MDR in these cancer cell lines (Table 1) by blocking the drug efflux function of P-gp. Here, PGP is linked to cancer.