A, Plasmids encoding HA-LOC73419 and Flag-RCAN1 were co-expressed in 293 cells. After IP of Flag-RCAN1, HA- LOC73419 is detected. The input lysate for the IP (4% of total) has been loaded in the first lane; comparison with the IP lane shows that the interaction of these two proteins in 293 cells is sub-stoichiometric. B, HA-LOC73419 and Flag-RCAN1 plasmids were co-transfected into Neuro-2a cells, with an unrelated control expression plasmid, producing Flag-USP21, serving as a negative control. IP was performed as in (A). Ha-LOC73419 is more efficiently pulled down by IP of Flag-RCAN1. The negative control Flag-USP21 shows no binding to Ha-LOC73419. The first lane shows 1% input; comparison with the results in (A) suggests that HA-LOC73419 interacts more efficiently with Flag-RCAN1 in Neuro-2a cells than in 293 cells.