Likewise, depletion of SPAG5 in the SUM-159PT triple-negative breast cancer cell line markedly reduced cell cycle-associated proteins, such as cyclin A, cyclin B (Supplementary Fig. 4E), and the cellular proliferation marker Ki-67 (Supplementary Fig. 4F), as well as counteracts mitotic spindle formation (Supplementary Fig. 4G). Here, SPAG5 is linked to triple-negative breast carcinoma.