Suspension cultures from Arabidopsis thaliana wild type and AtPIN1-deficient lines were initiated and maintained for more than 3 years. A protocol for efficient regeneration from long-term suspension cultures was established. Arabidopsis wild-type and respectively AtPIN1 mutant plants have been regenerated from these cultures and characterized. Additionally, transgenic suspension cultures expressing the uidA (beta-glucuronidase) reporter gene under the control of AtPIN1 promoter have been used for morphogenic studies. Our studies suggest that a lack of AtPIN1 function affects shoot differentiation and development, but does not influence in vitro regeneration of plants.