Fig 2: Schematic diagram of the mechanism through which IGFBP2 may regulate cell proliferation via the PI3K‐Akt signaling pathway. IGFBP2 activates IGF‐1 receptor (IGF‐1R) on the trophoblast plasma membrane, further activating actions downstream of the PI3K‐Akt signaling pathway to regulate cell growth and proliferation.

Fig 3: Effect of IGF1R‐PI3K‐Akt signaling pathway inhibitors on IGFBP2‐induced proliferation of HTR‐8/SVneo cells. Summary data showing cell viability (a, CCK8 assay) and relative mRNA expression levels (b–c) of proliferating cell nuclear antigen gene (PCNA) and Ki67 of HTR‐8/SVneo cells treated with solvent control (Control), 300 ng/mL IGFBP2 or IGFBP2 + picropodophyllin (PPP, 0.2 μM), IGFBP2 + ZSTK474 (0.1 μM, PI3K inhibitor), IGFBP2 + afuresertib (0.2 μM, Akt inhibitor) for 48 h (n = 5). OD represents relative optical density. The mRNA levels were normalized to 18S rRNA. Data represent the mean ± SD.

Fig 4: Application of IGFBP2 increases HTR‐8/SVneo cell proliferation. (a) A CCK8 assay was used to assess the viability of cells cultured with or without increasing concentrations (100, 200, 300 ng/mL) of IGFBP2 for 48 h (n = 5). OD represents relative optical density. (b–c) Summary data showing relative mRNA expression levels of proliferating cell nuclear antigen gene (PCNA) and Ki67 of HTR‐8/SVneo cells treated with or without IGFBP2 (300 ng/mL, n = 5). The mRNA levels were normalized to 18S rRNA. Data represent the mean ± SD.

Fig 5: Trophoblast IGFBP2 expression in decidual tissues from healthy women with normal pregnancies and recurrent spontaneous abortion (RSA) patient. (a–c) Representative images (a and b) and summary data (c) showing the expression of IGFBP2 in the trophoblasts indicated by arrows of decidual tissues from healthy women with normal pregnancies and RSA patient. Data showing the ratio of integrated optical density (IOD) divided by total area. The scale bar in (a and b) is 200 μm. Data are shown as the mean ± SD; n = 5.