Grb2 binds to the tyrosine phosphorylated design of BcrAbl by its SH2 domain, Survivin and interacts with proline rich reasons of Sos through its SH3 domains. Direct binding of Grb2 is necessary for the efficient induction of CML like myeloproliferative infection by oncogenic Abl protein and in other cancers. Apparently, Grb2 mutant proteins lacking D or C terminal SH3 domain might reduce Bcr Abl caused Ras activation and return the oncogenic phenotype. Thus, inhibition of Grb2 might subscribe to target the Bcr Ablexpressing cancer cells. Grb2 is definitely an adaptor protein and its functions are solely because of the existence of its binding SH2 and SH3 domains. On this foundation, and since SH2 or SH3 domains may represent targets for anti proliferative agents, we have created a peptide dimer in a position to concurrently bind to the two SH3 domains of Grb2 with high affinity, and it exclusively recognizes Grb2 biomedical library and doesn’t communicate with PI3KorNck, two SH3 domain containing adaptors. This peptidimer was conjugated with penetratin, the resulting molecule and a peptide sequence, denoted as peptidimer d in this paper, can prevent cancer cell growth in vitro but also indicates an anti tumor effect on mice xenografted with HER2 expressing human tumor. In this study, we have examined the mechanisms underlying the inhibitory aftereffect of the peptidimer h on K562 Bcr Abl good cell development. We have analyzed how this inhibitor produced its effect on cell proliferation and survival and examined the consequences of peptidimer c on K562 cell proliferation and apoptosis. We demonstrated that peptidimerc, which binds to Grb2 protein, inhibits proliferation of K562 by arresting the cells in S phase and causing cell apoptosis. Grb2 SH3 chemical conjugated to penetratin and penetratin were synthesized by solid phase peptide synthesis using Fmoc chemistry as described by Lymphatic system Cussac et al.. Gleevec1 was solution from Novartis, Switzerland. Phospho ERK1/2 antibody, phospho AKT antibody and AKT antibody were bought from Cell Signaling Technology Inc.. cyclin A, cyclin B1, cyclin D1, cyclin E, Cdk2, phospho Cdk2, Cdk1, phosphoCdk1, actin and Grb2 antibodies were acquired from Santa Cruz Biotechnology. K562 a cell line derived from a patient with CML blastic situation, was obtained from the Cell Bank of Chinese Academy of Sciences. Cells were maintained in RPMI 1640 containing 10% fetal bovine serum, 100 U/mL penicillin and 100 mg/mL streptomycin purchase AG-1478 in 5% CO2 atmosphere at 37 8C. For lysis, K562 cells were cleaned and gathered with cold PBS buffer. K562 cell lysate was prepared by homogenization in revised RIPA buffer and incubated at 4 8C for 30 min. Cell lysate was centrifuged at 13,200 rpm at 4 8C for 10 min, and the supernatant was stored at _20 8C. Protein concentration was determined with Bio Rad protein assay. Before electrophoresis, K562 mobile lysate was boiled for 5 min in 1_ SDS sample buffer containing five full minutes t mercaptoethanol.