LNX1 (Ligand of Numb, protein X 1) was originally identified as a binding partner of the cell-fate determinant Numb and was reported to be involved in ubiquitylation and degradation of Numb. LNX1 contains four PDZ domains and may function as a scaffold for a multi-protein complex. LNX1 has two splicing variants, LNX1p70 and LNX1p80. LNX1p70 has the N-terminal Numb binding region and four PDZ domains, whereas LNX1p80 has an additional RING-finger domain at the N-terminus followed by a Numb-binding region and four PDZ domains. This antibody can detect both LNX1p70 and LNX1p80, around 70-80 kDa and 80-100 kDa, respectively.