How cells deal with chromosome segregation errors. In normal cells, chromosome biorientation and proper kinetochore–microtubule (KT-MT) attachments are ensured by the SAC and a tension-dependent correction mechanism operated by Aurora B at centromeres throughout prometaphase and metaphase. In certain contexts, like cancer, some merotelic and syntelic KT-MT attachment errors can evade the correction machinery and satisfy the SAC, which may lead to anaphase laggards or misaligned chromosomes, respectively. Most anaphase laggards are transient and are proposed to result from unbalanced merotelic attachments. In these transient laggards, the differential transmission of forces generated by spindle elongation (F1 > F2) will stretch and elongate the kinetochore eventually, favoring segregation to the correct daughter cell, thus preventing chromosomal and genetic instability. Nevertheless, some merotelic attachments can be balanced (equal ratio of MTs toward each pole) and give rise to persistent laggards. The establishment of an Aurora B activity gradient at the spindle midzone in anaphase assists in spindle elongation, promotes the correction of attachment errors, and prevents aneuploidy and the formation of micronuclei. kMT, kinetochore microtubule.