Abstract Abstract 5087 Objective: Diffuse large B cell lymphoma (the diffuse large B-cell lymphoma, DLBCL), is one of the most common type of non-Hodhkin's lymphomawith high heterogeneity. γ-secretase can induce the hydrolysis of CD44, which play a key important in DLBCL, producing the CD44 intracellular domain. According to our research, the inhibition of CD44ICD can decrease the expression of NF-„KB and Stat-3 in SUDHL2 cell line from ABC-DLBCL cell line. Therefore the aim of this study was put important on the change of proliferation, apoptosis and main surface markers, ERK1/2 and phosphor-ERK1/2 in CD44 positive cell line from ABC-DLBCL after inhibiting the production of CD44ICD. Method: The surface expression of CD44 in SUDHL2 and OCI-ly3 cell lines was tested by flow cytometry, and then chose the CD44 positive cell line. Using 0. 1, 1. 0, 5. 0, 10, 25, 50, 75 and 100μM DAPT inhibited the production of CD44ICD in CD44 positive cell line respectively, and then tested the cell proliferation, apoptosis and main surface markers(CD44, CD19, CD20) by MTT analysis, Annexin V-FITC/PI and flow cytomety separately after 24h. mean while western blot was used to detected whether ERK1/2 and phosphor-ERK1/2 expressed in the chosen cell line, if they expressed in it, tested their change after blocking the release of CD44ICD for 1h. Results Conclusion The ERK1/2 signal path participated in the regulation of SUDHL2 cell line, moreover after inhibited the release of CD44ICD, both the ERK1/2 and phosphor-ERK1/2 could be regulated up, however further study must go on. Disclosures: No relevant conflicts of interest to declare.