Detection of CXCL4 and CXCL4L1 proteins in lysates and supernatants of HEK-293 transfectants. (A) Western blot analysis of lysate from mock (lane 1), CXCL4 (lane 2), and CXCL4L1 (lane 3) transfectants. Absence of immunoreactivity in mock lysate; strong immunoreactivity in lysate of a CXCL4 transfectant, and absence of protein in the lysate of a CXCL4L1 transfectant. One representative experiment is shown. (B) Western blot analysis of supernatant from mock (lane 1), CXCL4 (lane 2), and CXCL4L1 (lane 3) transfectants. Absence of immunoreactivity in mock supernatant, low immunoreactivity in supernatant of a CXCL4 transfectant, and strong immunoreactivity in the supernatant of a CXCL4L1 transfectant. One representative experiment is shown. (C) CXCL4/CXCL4L1 proteins in lysate from mock, CXCL4, and CXCL4L1 transfectants. Absence of protein in mock lysate, high protein levels in lysate of a CXCL4 transfectant, and absence of protein in the lysate of a CXCL4L1 transfectant, as assessed by ELISA. Cells were cultured for 24 hours in serum-free DMEM at a concentration of 5 × 10⁵ cells/mL medium as described in “Materials and methods.” Columns represent mean values (± SEM) of 4 experiments performed in 2 selected clones. (D) CXCL4/CXCL4L1 proteins in supernatant from mock, CXCL4, and CXCL4L1 transfectants. Absence of protein in mock supernatant, low levels of protein in supernatant of a CXCL4 transfectant, and high levels of protein in the supernatant of a CXCL4L1 transfectant, as assessed by ELISA. Cells were cultured for 24 hours in serum-free DMEM at a concentration of 5 × 10⁵ cells/mL medium as described in “Materials and methods.” Columns represent mean values (± SEM) of 4 experiments performed in 2 selected clones.