MYC and neoplasm: In summary, our findings reveal that (1) PEFs can be directly, rapidly and efficiently converted into piCLCs by ectopic expression of c-Myc alone; (2) at 45 out of the 51 injected sites, piCLCs produced stable homogeneous hyaline cartilage-like tissues without tumour formation and type I collagen expression after subcutaneous injection into nude mice, and piCLC-derived hyaline cartilage-like tissues remained in vivo for at least 16 weeks.