MAPK1 and plasma cell myeloma: In order to find out RAS related downstream signaling pathways changes after MMSA-1 expression was elevated, including proliferation pathway RAF/MEK/ERK as well as anti-apoptosis pathway RAF/PI3K/AKT, we performed a series of assays and found that hyperactivation of RAS led to phosphorylation of kinds of kinases including RAF, MERK, ERK-1 and ERK2, which in the end promoting myeloma cells proliferation.