Tumor suppressor which functions to suppress MRTFA-induced SRF transcriptional activity. May function in the RHOA-DIAPH1 signal transduction pathway and regulate cell migration through transcriptional regulation of ITGB1. Interacts with DIAPH1. Forms a nuclear ternary complex with MRTFA and SRF. Nuclear localization is required for inhibition of MRTFA. Expressed in most tissues tested with higher expression levels in brain, spleen and thymus. Belongs to the SCAI family. Truncated N-terminus.