RAP1GDS1 and cancer: However, more recent studies have determined that the generation of SmgGDS-607 and SmgGDS-558 is uniquely regulated in cancer cells (Brandt et al., 2020), and both splice variants contribute to malignancy (Berg et al., 2010; Schuld N. et al., 2014; Hauser et al., 2014; Gonyo et al., 2017; Brandt et al., 2020).