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. 1998 Nov 24;95(24):14179–14183. doi: 10.1073/pnas.95.24.14179

Figure 4.

Figure 4

(A) Dominant-negative PI 3-kinase constructs inhibit myogenesis. CEM were infected with RCAS, PR-A, or RCAS viruses expressing two dominant-negative mutants of the regulatory subunit of PI 3-kinase, p85ΔiSH2-N and p85ΔiSH2-C (43). The cells were cultured in MG medium for 3 days postinfection, followed by 2 days in MD medium to induce myoblast differentiation. Representative fields were photographed on day 5 (×6.5 objective, phase-contrast). (B) Dominant-negative PI 3-kinase mutants interfere with the induction of CK. CK activity was determined on day 6 in CEM cultures infected as described above or infected with RCAS-v-P3k as a positive control. Mean ± SE values were from two experiments with three replicate assays. (C) Dominant-negative PI 3-kinase mutants inhibit the expression of muscle-specific proteins. Muscle-specific protein levels were studied in the cells on day 6 postinfection with PR-A (lane 1), RCAS (lane 2), RCAS-p85ΔiSH2-N (lane 3), or RCAS-p85ΔiSH2-C (lane 4) viruses and assayed by immunoblot as in Fig. 2B. Similar results were obtained in three replicate experiments.