AKT1 and plasma cell myeloma: Qiang et al (2002) have also seen this crosstalk in human myeloma cells. They showed that the phosphorylation of MEK1/2 was also inhibited but not that of Raf, an upstream kinase of MEK1/2, suggesting that the effect was at the level of MEK1/2. In contrast, two groups reported that Akt could influence the phosphorylation of Raf in other cell types, thereby regulating the MEK–ERK pathway (Wennstrom and Downward, 1999; Zimmermann and Moelling, 1999).