Updated project metadata. SMPD4 is a neutral sphingomylinase implicated in a specific type of congenital microcephaly. Although not intensively studied, SMPD4 deficiency has also been found to cause cell division defects. This suggests a role for SMPD4 in cell cycle and differentiation. In order to explore this role we used proximity ligation to identify the partners of SMPD4 in vivo in HEK293T cells. We found that these partners localize near the endoplasmic reticulum ( ER) and the nuclear membrane. Using mass spectrometry we could identify these partners and discovered that SMPD4 is closely asso-ciated with several nucleoporins, including NUP35, a nucleoporin directly involved in pore membrane curvature and pore insertion. This suggests that SMPD4 may play a role in this process.