Fig. 4.

Class 1A PI3K deficiency causes delayed and decelerated tumorigenesis. (A) Percentage of mice with large tumors exceeding 600 mm³. 8.5 × 10⁵ B16-F1 melanoma cells were injected into the rear flanks of wild-type and heterozygous mice, and tumor volume was measured daily. Wild-type mice grew large tumors as early as 10 days after injection. By day 28, 79% of wild-type mice bore large tumors. By contrast, heterozygous mice were delayed in large tumor formation; tumors were not observed until day 16. By day 28, only 48% of these mice bore large tumors. (B) Tumor growth rates varied between wild-type and heterozygous mice. (a) The tumor growth rates in wild-type mice were fast and synchronous, with most mice achieving maximal tumor volumes by day 16. (b) The tumor growth rates in heterozygous mice were slow and asynchronous, with maximal tumor volumes achieved often only after day 20. Nine of 25 mice (36%) failed to grow tumors or had tumors that regressed.