Multiple residues in the novel CTS are crucial for chimeric proteins targeting to primary cilia. A) Schematic representation of CD16.7 fused with the 8-residue CTS bearing different point mutations or 2 4-residue sequences within the CTS. B) Expression of indicated constructs in A in the primary cilia of IMCD3 cells. Cells were stained by antibodies against CD16 (green) and acetylated α-tubulin (Ac-α-tub; red). Scale bar, 5 μm. C) CD16-positive cilia were quantified for all constructs in B. D) Expression of CD16.7 fused with either the novel 8-residue CTS or the first 4 key residues of the CTS in the primary cilia of IMCD3 cells. Scale bar, 5 μm. E) Quantification of percentage of CD16-positive cilia in cells. Error bars represent the sd between microscope fields from ≥3 independent experiments. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 compared with CD16.7-CPC1-PP1 control.