In breast cancer cell lines, hypermethylation caused silenced SLIT3, which was re‐activated after treating with 5‐aza‐2′‐deoxycytidine Moreover, re‐activation of SLIT3 inhibited the growth and migration of breast cancer cell lines; thereby, it appeared to function as a novel cancer suppressor gene [56]. This evidence concerns the gene SLIT3 and breast cancer.