Given the task definition and input, reply with output. Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

Abstract: Injection of homologous DNA sequences into nuclei of cultured mammalian cells induces mutations in the cognate chromosomal gene. It appears that these mutations result from incorrect repair of a heteroduplex formed between the introduced and the chromosomal sequence. This phenomenon is termed 'heteroduplex induced mutagenesis'. The high frequency of these events suggests that this method may prove useful for introducing mutations into specific mammalian genes.
Introduction of homologous DNA sequences into mammalian cells induces mutations in the cognate gene.