MAPK8 and breast cancer: We further found that in hOBs CD99 activation induces AKT and ERK phosphorylation, consistent with data demonstrating the ability of CD99 stimulation to induce MAPKs and protein kinase C activation [52, 53] and findings showing that, in human breast cancer cells, CD99 promotes SRC, AKT, ERK, and JNK activation, thus increasing JUND and FOSB AP-1 transcription factors expression [15].