A. Structural formulas of LPA, OTP, and the LPA2-specific agonists DBIBB, RP-1, and RP-2. B: Kaplan-Meier survival plots for groups of 15 C57BL/6 mice exposed to 15.69 Gy of 137Cs γ-irradiation using a partial body 5% bone marrow shielding model. DBIBB was dissolved in 1% ethanol/2% propanediol in PBS (vehicle) and was administered starting at +26 ± 2 h postirradiation for 3 days as a single daily subcutaneous injection. DBIBB increased survival during the GI-ARS phase (days 8–12) and also the HEM-ARS phase (days 15–20) [see Patil et al. (21) for details]. C: Effect of RP-1 on the survival of small intestinal enteroids after 5 Gy γ-irradiation. Enteroid cultures were established for 6 days before treatment with 1 μM RP-1 or vehicle. On day 7, the cultures were exposed to 5 Gy γ-irradiation and allowed to grow for 2 more days before the surviving enteroids were counted. Data points are the means of triplicate wells and the results are representative of at least three biological replicates (*P = 0.05, **P ≤ 0.01, ***P < 0.001). Panel C is taken from Kuo et al. (14).