RO4929097 is a γ secretase inhibitor with IC50 of 4 nM, inhibiting cellular processing of Aβ40 and Notch with EC50 of 14 nM and 5 nM, respectively. 

RO4929097 decreases the amount of Aβ peptides secreted into the culture medium in HEK293 cells with EC50 of 14 nM. RO4929097 strongly inhibits Notch processing with EC50 of 5 nM in the Notch cell-based reporter assay. The potency of RO4929097 in cell-free and cellular assays is in the low nanomolar range with >100-fold selectivity observed with respect to 75 other proteins of various types including receptors, ion channels, and enzymes (CEREP panel). After 5 days of treatment, RO4929097 reduces the production of ICN in the human NSCLC A549 cells inducing a flattened and less transformed tumor cell phenotype in tissue culture.RO4929097 blocks Notch processing in human non-small cell lung carcinoma cells and decreases expression of the Notch transcriptional target gene Hes1. Treatment with RO4929097 reveals a two- to threefold decrease in the expression of direct Notch target genes, Hes1, Hey1, and Heyl in SUM149 and a 3.5- to eightfold decrease in expression in SUM190 cells. RO4929097 modestly inhibits the growth of SUM149 cells in a dose-dependent manner. At a concentration of 1 μM of RO4929097, growth inhibition is 20 % for SUM149 and 10 % for SUM190 cells, relative to vehicle-treated controls. RO4929097 decreases the production of inflammatory cytokines by T-cells. Furthermore, with RO4929097 treatment, there is a shift in favor of TH2 over TH1 cytokines. In addition, T-cell activation induced IL-6 production would be increased with RO4929097. Upon RO4929097 treatment, the selected melanoma cell lines reveals downregulation of NOTCH downstream effector HES1. A decrease in the amount of melanospheres formed upon RO4929097 treatment in primary melanoma cell lines is detected.