CCL21 and breast carcinoma: Moreover, because the PI3K inhibitor Ly294002 also blocked the CCL21 induced MAPKp42/44 phosphorylation in HS578T-Hyg cells (Figure 2A), but did not alter the cells migratory behavior these data suggest that MAPKp42/44 signaling is not involved in the migration of HS578T-Hyg breast cancer cells.