Required for MAP kinase p38 (MAPK11, MAPK12, MAPK13 and/or MAPK14) activation during gastrulation. Required for down-regulation of E-cadherin during gastrulation by regulating E-cadherin protein level downstream from NCK-interacting kinase (NIK) and independently of the regulation of transcription by FGF signaling and Snail. Required for starvation-induced ATG9A trafficking during autophagy. Interacts with ATG9A (By similarity). Interacts with MAPK14. Ubiquitously expressed throughout development. Mice show gastrulation defects in which mesoderm migration is defective due to deficiency in E-cadherin protein down-regulation in the primitive streak. A weaker mutation named droopy eye (drey), which affects splicing causes incompletely penetrant defects in neural tube closure, eye development and gastrulation. Belongs to the SPT20 family.