Among the 60 down‐regulated proteins in mice that developed mammary tumours (compared to CANRegress mice) were neural cell adhesion molecules and synaptic plasticity‐associated proteins, including cadherin‐2 (Cdh2), cell adhesion molecule 1 (SynCam1), neuroligin‐3 (Nlgn3), synaptotagmin‐2 (Syt2), FAM79A (Mover) and the voltage‐gated potassium channel (Kcna2) (Figure 11E–J). Here, CHL1 is linked to breast cancer.