Cartoon illustrating the recognition of Nek2A by APC/CMCC. KEN box and D box dependent substrates such as securin and cyclin B do bind APC/CMCC. In contrast, cyclin A and Nek2A bind APC/CMCC-open. Cyclin A is ubiquitinated by UbcH10 and Nek2A has more chances of being ubiquitinated once bound to the APC/CMCC-open by using both UbcH10 and UbcH5. The positioning of UbcH5 with respect to the APC/C catalytic site is based on mutagenesis data 