Phps1

The anti-KIR2DL4 agonistic antibody (mouse monoclonal IgG, Clone; 181703) was purchased from R&D Systems (Minneapolis, MN). Another anti-KIR2DL4 antibody (rabbit IgG, polyclonal, ab154386) and an anti-phospho-SHP-2 antibody (Y542, rabbit polyclonal IgG), used for immunostaining and Western blotting were obtained from Abcam (Cambridge, MA). An anti-phospho-ERK antibody and an anti-GAPDH antibody were obtained from Cell Signaling Technology (Beverly, MA). The KIR2DL4-targeted shRNA lentiviral particles and the control particles were purchased from Santa Cruz Biotechnology (San Diego, CA). Infection of these viral particles and the following selection were performed according to the manufacturer's instructions. The specific MAP2K1 inhibitor U0126, the specific ERK inhibitor FR180204, and the specific SHP-2 inhibitor PHPS1 were purchased from Santa Cruz Biotechnology [22 (link)–24 (link)]. We used all inhibitors at concentrations of 10 µM.

Control and SLAMF8-KD ALCL cells were cultured for 24 h at 1–3 × 10⁴ cells/100 µL/well in RPMI1640 + 10% FCS. In a separate experiment, ALCL cells were cultured for 24 h at 1–3 × 10⁴ cells/100 µL/well in the presence of dimethyl sulfoxide (DMSO) or the SHP-2 specific inhibitor PHPS1 (Santa Cruz Biotechnology) at 10 μM.^{9 (link)} The Cell Counting Kit-8 (Dojindo, Kumamoto, Japan) was used to evaluate growth by measuring absorbance at 450 nm. The relative absorbance was calculated based on the absorbance of control cells or DMSO. Three individual experiments were performed.