BRF2 and squamous cell lung carcinoma: In TIMM23-knockdown human embryonic kidney 293 T (HEK293T) cells, undegraded PINK1 accumulated (Fig. 5B), whereas TIMM23 expression remained unchanged in lung squamous cell carcinoma cell lines H226 and H520 despite variations in BRF2 and SLC8A3 levels (Fig. 5C).