In another study, a 2.5-fold increase in activated MAPK was seen in breast cancer specimens compared to normal breast tissue, and this was associated with poor prognosis and decreased sensitivity to endocrine therapy, and with expression of phosphorylated c-jun, a transcription factor activated by MAPK (Gee et al, 2000; Donovan et al, 2001). Here, JUN is linked to breast cancer.